The cost could go to a specific credit card fee paid by the customer only when they use credit cards, but the merchant agreements typically prohibit you from do

The cost could go to a specific credit card fee paid by the customer only when they use credit cards, but the merchant agreements typically prohibit you from doing that. You're paying the price whether or not you're getting the convenience. (I've seen a few small merchants tackle this by offering a cash discount as a subtraction from the regular price, for instance. But I'm not sure even that is contractually permitted.)