Also, I don’t see how using one bank would solve the problem. Unless you act as a central authority, the parties involved in it needs to be benefited. So, even if you buy a bank, unless you get the merchant and the end consumer to use your payment method, there is someone involved apart from you who needs to make money in a transaction. Who will pay them ?
This is where wallets come in (not crypto wallets, paytm, ola, freecharge wallets), so the transaction can happen inside a closed system. This is also the reason why wallets have 0 charges for incoming money, and charges for outgoing money. So, you don’t need a cryptocurrency to solve the problem, just a wallet that everyone would use.
Correct me if I am wrong.