Ok, so what you're saying then is that a bank should be allowed to discriminate based on our purchases, and that if we don't like it, either use debit or cash,

Ok, so what you're saying then is that a bank should be allowed to discriminate based on our purchases, and that if we don't like it, either use debit or cash, which come with some flaws/inconveniences. How about instead of allowing to discriminate based on purchases, they just accept slightly smaller margins?