I’m thinking either Jake has some sort of allowance or stipend, and is exaggerating when he says he “doesn’t have money”
I mean, having walking around money and having Mom-style "now that's walking around money" (i.e. enough to buy a Willy Mays rookie card) are two different things.
...to the point that they somehow got away with giving Quark, of all characters, the moral high ground when criticizing human history.
Honestly, your "the most stable and ethical expression of capitalism" thesis has made me realize just how right Quark was. With humanity, the wealth gained through unchecked capitalism inevitably gets parleyed into political power that destroys the free market that enabled it in the first place. For Ferengi society to be stable, that dictatorial tendency would have to be absent, which means they really are better.
I'm very unclear on what exactly makes "transporter credits" or "labor vouchers" different from "money."