Payment providers hate money and love when you give a business a credit card rather than cash. Small business's where I live (Canada) are charged anywhere from 2-4% of the purchase price in fees to accept a credit card.
If you travel and let's say a BnB refuses to accept your Amex card, it's not that they can't take it, they don't want to because the fees are so high. When you pay for fuel and pay with a CC, the business makes very little on already tight margins.
There are definitely significant financial interest behind keeping the system the way it is. When you use cash, no institution but the seller makes a profit. When you use a card ...