The OP article itself explains the history

> The core problem has always been fragmentation. Each EU country developed its own domestic payment solution — Bizum in Spain, iDEAL in the Netherlands, Payconiq in Belgium, Girocard in Germany — but none could work across borders. A Belgian consumer buying from a Dutch retailer still needed Visa or Mastercard. National pride and competing banking interests repeatedly sabotaged attempts at unification.

> The network effect compounds the challenge. Merchants accept Visa and Mastercard because consumers carry them. Consumers carry them because merchants accept them. Breaking that loop requires either regulatory force or a critical mass of users large enough to make merchants care — which is precisely what the EuroPA deal attempts to deliver by connecting existing national user bases rather than building from scratch.