Comment by MichaelDickens

The credit card fee is the only thing that changes based on the payment method. The fuel cost, employee cost, etc. is the same for the same product, but if you pay with a credit card, it costs the seller more money.

It's common for the price you pay to change when the method of purchase changes. For example, having a product delivered costs the seller more than if you picked it up from the store, so you have to pay a delivery fee.