with playspan discontinued will hurt the game

[Chihaya]

You didnt think you could spend money that isnt yours without some kind of fee did you? How else do you think CC companies stay in buisness?

Here, the processing fee is paid by the business sellers, in this case - SE, not you.
As a consumer, unless you get a card with annual fee or minimal usage fee, you don't have to pay anything unless you keep an unpaid balance.

I pay my cards off at the end of the month, have yet paid AMEX/VISA/Discover anything extra other than foreign transaction fees, which is about 2.5~3%.

They stay in business by those processing fees from the merchants and collecting interest of unpaid balances.