Like the article mentioned many EU countries have their own payment systems. The challenge is not to build something from the scratch but rather to make existing solutions interoperable. The first talks about cross-border integrations started many years ago but they went very slowly. However, some work is being done, just a week ago a first transfer was done from Spanish Bizum to Polish Blik.

If there's anything the EU is good at, it's inter-op in markets.