>what do Visa and MasterCard even do? They are the telephone wires for your calls, basically. >I assume they have a few datacenter that do trillions of little

>what do Visa and MasterCard even do? They are the telephone wires for your calls, basically. >I assume they have a few datacenter that do trillions of little lookups, but is that all there is to it? They also blackmai-- sorry, convince merchants to accept their services for a fee because look how many people pay with Visa/Mastercard! >What stops a big bank from doing whatever it is they do? Nothing. See American Express and Discover which are both banks and payment networks because they like taking the entire pie (and presumably do a lot less blackmai-- sorry, convincing).