Comment by Shinkei

Can somebody ELI5 why Square wouldn't develop infrastructure to 'cut-out' Mastercard/Visa from this transaction? I mean, it seems like they could issue a credit card to begin competing with existing brands. I guess I just don't understand enough about these 'interchange' fees. So does the customer's bank or storefront's bank pay for this transfer? If this is infrastructure similar to broadband lines, are they monopolistic or could a competing company lease bandwidth on the same lines?