Considering how much of a rip off they already are on the financial system. Simple rent seeking at 23% interest, 20% + 3% processing. There should be legislation to combat this shit.
If you struck down the rules about providing different prices based on payment type and did a 10% discount by paying in cash, you'd be surprised how quickly things would change.
Pretty sure the 20% interest goes to the bank and the 3% fee goes to the processor. They’re not the same entity.
Does the card processor get any of the interest? I don't think the system works like that.