Card fees have both a variable (X percent) and fixed (Y cents) portion. For example, a transaction using a Visa credit card might cost 2.7% plus $0.10.

Not forgetting it but it doesn’t move the needle much. If you assume an average card transaction size of $10, which is likely higher. That is only 0.3% of processing which may increase revenue by 30% at best.

You're off by an order of magnitude - $0.30 of $10 is 3%, which overshadows the 0.8% by quite a bit. Although I agree that $10 is most likely a low estimate, I'd expect $0.30 per charge to have a very non-trivial impact.

Well spotted. My quick math was very incorrect. Thanks for the correction