As for rewards on MC and Visa, which card are you on? In my experience, either the rewards are very small, or they are for specific retailers only, where the Bank has done a deal directly with the merchant. Occasionally they are a loss leader for the bank, working on the principle that you are
The article is wrong about the UK capping interchange fees. Removing the EU cap was one of the first EU rules that the government decided to abolish after Brexit. At one point it meant you weren't going to be able to use a Visa card with Amazon, you'd have to switch to Mastercard.