This is EXACTLY the point.

This is EXACTLY the point.

The easiest explanation I have seen of what the process looks like is at Ars Technica.

http://arstechnica.com/gadgets/2014/10/how-mobile-payments-really-work/

In short, the banks are unlikely to build something themselves, but rather piggy back on a system from Mastercard or Visa (or just stick with Google and Apple). The banks will only do it if they think it will be more profitable or if it will give them some edge on the other banks.