The credit card companies have always tried to prevent merchants from doing this by inserting language prohibiting either credit card surcharges or cash discounts into the contract agreements with the merchants. Obviously, credit card companies want to make it easy and convenient for consumers to use their credit cards.

I can’t immediately find it, but at some point I think 10-15 years ago, some merchants sued the credit card companies over this, and they won a court ruling that said that the clauses forbidding cash discounts and surcharging are unenforceable. As a result, merchants are now free to do it, but there are various rules. And some state legislatures have started to get involved with regulating things.