Merchants are not liable for fraud at the POS (which includes almost all restaurants, except maybe those doing deliveries or taking down payments for reservations via the phone etc.)
Pretty much everything except for credit cards and ACH are really using one of those two behind the scenes, whereas what you want is something that allows you to transfer money using ACH-level fees without the totally unnecessary ACH misfeature that you can't revoke merchants or predefine limits on how much they can charge.
But that's where the "Visa has captured the regulators to prevent things like that from existing" problem comes in.
> The biggest whiners about fees are small businesses
The biggest whiners about fees are small businesses because a) they have very thin margins to begin with, so 3% often means that Visa is taking more of the sale price than they keep themselves and can be the difference between a sustainable business and bankruptcy, and b) larger companies can negotiate deals and pay less than 3%, which creates another competitive advantage for big business that small businesses can't achieve, which small businesses rightfully dislike.
3% sounds like a small number until you're talking to someone with a 5% profit margin before they lose 3% of revenue to the credit card companies. Then you're telling them that they shouldn't care about losing 60% of their personal income to corrupt banking laws.
The price discovery stuff is pretty obvious. Do business with PayPal. It works great… until PayPal arbitrarily decides to freeze your account. Use Venmo or cash app… except sellers will pressure you to treat it like a gift vs. a purchase. You can use ACH, but now some random company has access to your checking account.
Or… you can use a credit card, probably get a 2% kickback, and the merchant pays like 3% unless they’re in a high risk business. If there’s a problem like fraud, the bank eats it.
The biggest whiners about fees are small businesses, especially restaurants. These are businesses where it’s super easy to launder cash and avoid tax reporting.