EU & UK cap it at 0.3% (0.2% for debit cards), and the rest of the world are closer to EU than US fees, if I understand correctly.
The power of the free market.
suggests that was not the GP's point.
American Express leverages the fact that most consumers don’t care what the merchant is charged
The clause that doesn't allow passing fees on the customer is the only thing that makes market non-free.
I think it would be only fair if people paying with a card were charged more. They get the cash back from the bank anyway.
Also I know that there are super-discounted stores in my country that do not accept cards for this reason.
This changed a while back.
"merchants are fee-insensitive, while consumers are rewards-sensitive. In other words, consumers pick credit cards (and, indirectly, networks) based on the goodies they receive, and stores will grudgingly tolerate high fees in order to accept credit cards."