Let's suppose that network A charges the merchant 3%, while network M charges 1.5%, and network D charges 0.75%. Shouldn't the merchant be able to steer customers to use network D? When merchants are able to show customers the relative costs of different payment methods the processing networks will have a powerful incentive to compete with each other on price. This isn't about cards vs cash, this is about which card provides the best value.
But what if my Visa Infinite (which earns rewards) uses network A, and Visa Gold (no rewards) uses network D?
Card numbers
45140116xxxxxxxx
45121100xxxxxxxx