Earlier quoted context omitted.
In India, the cost of instant payments is exactly zero. Additionally, RuPay cards have a Zero MDR which has really really made Visa and MasterCard angry
So what do you pay with? Your transaction data? Subscription to other services?
For the apps like GPay and Amazonpay, yes it is data. But of course there is the reference implementation app that does not do any of that. People just prefer the other apps because they offer good cashbacks.
For the banks, it's a service they offer, just like having a website and passbook updation. No customer is going to go to a bank without a website and now the same applies for instant transfer.