In reply to David Froud.

And, is that not what "tokenisation" does, secure the "insecure" card number?
The "card brands" are the "highway" that the world's banks can communicate with each other in "real time"; all those individual banks still need such a system (the alternative is the clunky ACH system), and there are two of them, MasterCard and Visa, both originally developed by groups of banks; those two card companies invariably do the research and development of the system on behalf of all the partner banks—think about it; and, why do you think that Apple is riding on the back of the credit card companies rather than inventing their own proprietary "highway" as they usually do? Because that system works!