Each country central bank should have its own national payment processing system. Why is this not a thing? Spain has Bizum, for example.
One thing to note is that by design, the US banking system is very decentralized and that makes any sort of migration or mandate like herding cats. There are 141 banks in Spain and 4135 in the US.
US banks are generally not allowed to exceed 10% of deposits through mergers and there are only three passing that threshold; JPMorgan Chase at 15%, BofA at 14%, and Wells Fargo at 11%.
[0] https://www.ecb.europa.eu/paym/integration/retail/instant_pa...
The IPR is a regulation that requires banks to support instant payments and offer them to customers.
[0]: https://www.ecb.europa.eu/paym/target/tips/html/index.en.htm...
Their transaction fee is quite cheap, so small businesses earn more money and reinvest their revenue, rather than having it taken by Visa or Mastercards.