When did banks actually make that switch?
It must be relatively recent, because I remember not that long ago my credit union ATM card was not part of Mastercard. Now I have a new one and it suddenly has a Mastercard logo.
… banks saw big, no, BIG $$$ and lost their minds. The transition was rather swift: between the very late 2000's and approximately 2015 (give or take a few years), the transition had been complete. Credit cards became a massively profitable and booming business for the banks, with all sorts of loyalty programmes and bonuses (at consumers’ expense, of course, as the banks also jacked up interest rates on revolving credits). Note that all of this took place before national governments stepped in to regulate the transaction fees.
This coincided with the growing allergy of Western governments to owning any critical infrastructure (including payment networks) and the rising trend of outsourcing as much as possible to the private sector. As it is easy to imagine, it did not take long for the national banks already being in bed with Visa/MC to convince their respective national governments to stop investments in maintenance and enhancement of domestic payment networks and delegate the payment processing to the cartel: «they can do it better than you do».
… all of which has led us to where we are right now. Technically, national payments are still alive, but they are more in the contained mode of operation and not in active use or development.