> Nobody is denying it costs money, the problem is it's not proportional to the value they add, nor their costs.

The value they add is much greater than their costs. People who deny this lack a lot of imagination to ponder how inconvenient things could be without credit and debit cards.

But we don't need to imagine: If Visa and Mastercard didn't add more value than they cost, then merchants wouldn't accept them. It is still 100% voluntary for a merchant to decide if they want to accept cards or not. Which is a freedom they should have. These cards aren't legal tender.