Engineering wise, it's a miracle that UPI works. All of the banks have very little in the way of consistency checks and proper abstractions. Everything is superglued together and very brittle. There was clearly little direct communication between NPCI, the issuing banks, and the users of the apis in development.

I agree with India's protectionist attitudes that's kept Western companies from monopolizing the ecosystem though. It works well enough, much to chagrin of SV tech companies lol.