They charge you extra, they just make it invisible. The store has to pay the fees and it causes prices to go up for everyone to cover them.

> A U.S. retailer told me the credit card companies won't allow that in the U.S.?

That used to be the case, but it's not current. Merchants can charge a credit card fee, and many do. Many merchants near me (washington state) don't, but those that do add a fixed fee of 1-3% for credit.

They can't make it an explicit line item of "3% surcharge" or whatever. Instead, the business will raise prices across the board and offer a "cash discount" of 3%