That hidden cost is subsidized by the other customers charged the same price but that pay cash, or via debit card rather than credit card, or even with a credit card with lower rewards than yours.

As a merchant that accepts credit cards, I can say that the vast majority of the money comes in via credit cards themselves, and costs 3% in fees. It absolutely comes out of the customer's pocket at the end of the day.

Okay, when you originally you wrote you were effectively paying 2–3% in fees on every transaction for this privilege [the buffer between your actual money and the merchant, quoting the post you were replying to], I took it to implicitly mean every credit card transaction.

If what you really meant is that the cost of the credit card transaction is implicitly in the price everyone is being charged, then sure, I see your point -- except that I think it actually strengthens the original poster's argument for using credit cards! If you pay $25 for a widget in cash and I pay $25 for the same widget on my credit card, then we're literally both paying the same price, but I'm getting the ostensible benefit of using the credit card and you're not. (I would actually argue, unlike the OP, that this is mostly true for debit cards as well, in that you still have a bank fighting to get your money back in a way that isn't true with cash.)

In Australia now, the restriction that Visa/MC used to enforce (same price for cash or CC) has been changed by the Reserve Bank (AU equiv of the Fed) so that surcharges etc are visible. So these days most merchants apply a ~1% surcharge for CC transactions.

We also have an "EFTPOS" network that is independent of Visa/MC. It's a debit account network owned by the banks that give you access to savings or cheque accounts. It's charges are much lower than Visa/MC, so merchants like when you use it and don't apply a surcharge.