Several have. Brazil's central bank built Pix, now used by about 150 million people; India's public UPI rail runs across 703 banks and carries close to half the world's real-time payments; and Kenya's M-Pesa turned mobile money into a national rail used by 37.9 million people.
The pattern is public or shared infrastructure, not a private app: a rail built once that every bank and wallet plugs into.
That is why adoption ran to most of the adult population in years, and why the same model is spreading across the Global South.