|the Borro ad was the next one to the left|
The orthodox view is that the level of "real" economic activity is determined by "real" factors -- endowments, tastes, technology -- and people simply hold money balances proportionate to this level of activity. In this view, a change in the money supply can't make anyone better or worse off, at least in the long run, or change anything about the economy except the price level.
Just looking at these ads shows us why that can't be true. First of all, the question of what constitutes money. All three of these ads are, in effect, inviting you to use something as money that you couldn't previously. Without the specialized intermediary services being hawked here, you couldn't pay the startup costs of a business with a necklace (what's this thing made of, plutonium?), or pay for a subway ride with a promise to pay later, or pay for much of anything with a used couch. And this new liquidity has real benefits -- otherwise, no one would be buying it, and it wouldn't be worth the cost of producing (or advertising) it. The idea -- stated explicitly in the Borro ad -- is that the liquidity they provide allows transactions to take place that otherwise wouldn't. The ability to turn a piece of jewelry or a car into cash allows people to use productive capacities that otherwise would go to waste.
And of course this makes sense. The orthodox view is that money is useful -- there must be a reason that we don't live in a barter world, and more than that, that all this huge industry of liquidity provision exists. But money, for some reason, is not subject to the same kind of smoothly diminishing returns that other useful things are. There is a fixed amount you need, you can't get by with less, and there's no benefit at all in having more. The problem is worse than that, since the standard view is that money demand is strictly proportionate to the volume of transactions. But, which transactions? Presumably, the amount of economic activity depends on the availability of money -- that's what it means to say that money is useful. And furthermore, as these ads implicitly make clear, some transactions are more liquidity-intensive than others. No one is offering specialized intermediary services to help you buy a hamburger. So both the level and composition of economic activity must depend on money holdings. But in that case, you can't say that money holdings depend only on the volume of activity -- that would be circular. In a world where money is used at all, it can't be neutral. An increase in the money supply (or better, in liquidity) may raise prices, but it won't do so proportionately, since it also enables people to benefit from increasing their money holdings (or: shifting toward more liquid balance sheet positions) and to carry out liquidity-intensive transactions that were formerly unable to.
This is a very old issue in economics. The idea that money should be neutral is as old as the discipline, and so is this line of criticism of it. You can find both already in Hume. In "Of Money," he lays out the argument that money must be neutral in the long run, since it is just an intrinsically meaningless unit of measure; real wealth depends on real resources, not on the units we count them in. Unlike most later writers, he follows this argument to its logical conclusion, that any resources devoted to liquidity provision are wasted:
This has made me entertain a doubt concerning the benefit of banks and paper-credit, which are so generally esteemed advantageous to every nation. That provisions and labour should become dear by the encrease of trade and money, is, in many respects, an inconvenience; but an inconvenience that is unavoidable, and the effect of that public wealth and prosperity which are the end of all our wishes. ... But there appears no reason for encreasing that inconvenience by a counterfeit money, which foreigners will not accept of in any payment, and which any great disorder in the state will reduce to nothing. There are, it is true, many people in every rich state, who having large sums of money, would prefer paper with good security; as being of more easy transport and more safe custody. ... And therefore it is better, it may be thought, that a public company should enjoy the benefit of that paper-credit, which always will have place in every opulent kingdom. But to endeavour artificially to encrease such a credit, can never be the interest of any trading nation; but must lay them under disadvantages, by encreasing money beyond its natural proportion to labour and commodities, and thereby heightening their price to the merchant and manufacturer. And in this view, it must be allowed, that no bank could be more advantageous, than such a one as locked up all the money it received, and never augmented the circulating coin, as is usual, by returning part of its treasure into commerce.You can find similar language in "On the Balance of Trade":
I scarcely know any method of sinking money below its level [i.e. producing inflation], but those institutions of banks, funds, and paper-credit, which are so much practised in this kingdom. These render paper equivalent to money, circulate it throughout the whole state, make it supply the place of gold and silver, raise proportionably the price of labour and commodities, and by that means either banish a great part of those precious metals, or prevent their farther encrease. What can be more shortsighted than our reasonings on this head? We fancy, because an individual would be much richer, were his stock of money doubled, that the same good effect would follow were the money of every one encreased; not considering, that this would raise as much the price of every commodity, and reduce every man, in time, to the same condition as before. ...
It is indeed evident, that money is nothing but the representation of labour and commodities, and serves only as a method of rating or estimating them. Where coin is in greater plenty; as a greater quantity of it is required to represent the same quantity of goods; it can have no effect, either good or bad, taking a nation within itself; any more than it would make an alteration on a merchant’s books, if, instead of the Arabian method of notation, which requires few characters, he should make use of the Roman, which requires a great many.From this view -- which is, again, just taking the neutrality of money to its logical conclusion -- services like the ones being advertised on the F train are the exact opposite of what we want. By making more goods usable as money, they are only contributing to inflation. Rather than making it easier for people to use necklaces, furniture, etc. as means of payment, we should rather be discouraging people form using even currency as means of payment, by reducing banks to safe-deposit boxes.
That was where Hume left the matter when he first wrote the essays around 1750. But when he republished "On the Balance of Trade" in 1764, he was no longer so confident.  The new edition added a discussion of the development of banking in Scotland with a strikingly different tone:
It must, however, be confessed, that, as all these questions of trade and money are extremely complicated, there are certain lights, in which this subject may be placed, so as to represent the advantages of paper-credit and banks to be superior to their disadvantages. ... The encrease of industry and of credit ... may be promoted by the right use of paper-money. It is well known of what advantage it is to a merchant to be able to discount his bills upon occasion; and every thing that facilitates this species of traffic is favourable to the general commerce of a state. But private bankers are enabled to give such credit by the credit they receive from the depositing of money in their shops; and the bank of England in the same manner, from the liberty it has to issue its notes in all payments. There was an invention of this kind, which was fallen upon some years ago by the banks of Edinburgh; and which, as it is one of the most ingenious ideas that has been executed in commerce, has also been thought advantageous to Scotland. It is there called a Bank-Credit; and is of this nature. A man goes to the bank and finds surety to the amount, we shall suppose, of a 1000 pounds. This money, or any part of it, he has the liberty of drawing out whenever he pleases, and he pays only the ordinary interest for it, while it is in his hands. ... The advantages, resulting from this contrivance, are manifold. As a man may find surety nearly to the amount of his substance, and his bank-credit is equivalent to ready money, a merchant does hereby in a manner coin his houses, his household furniture, the goods in his warehouse, the foreign debts due to him, his ships at sea; and can, upon occasion, employ them in all payments, as if they were the current money of the country.Hume is describing something like a secured line of credit, not so different from the services being advertised on the F line, which also offer ways to coin your houses and household furniture. The puzzle is why he thinks this is a good thing. The trade credit provided by banks, which is now "favourable to the general commerce of the state," is precisely what he was trying to prevent when he wrote that the best bank was one that "locked up all the money it received."Why does he now think that increasing liquidity will stimulate industry, instead of just producing a rise in prices that will "reduce every man, in time, to the same condition as before"?
You can't really hold it against Hume that he never resolved this contradiction. But what's striking is how little the debate has advanced in the 250 years since. Indeed, in some ways it's regressed. Hume at least drew the logical conclusion that in a world of neutral money, liquidity services like the ones advertised on the F train would not exist.
 I hadn't realized this section was a later addition until reading Arie Arnon's discussion of the essay in Monetary Theory and Policy from Hume and Smith to Wicksell. I hope to be posting more about this superb book in the near future.