> For purchases, the US has debit cards and Zelle.
Both are a very poor alternative to something like UPI or even EU-style bank transfers as a mass retail payment system. Cards are orders of magnitudes more expensive; Zelle has no standardized interface and is explicitly geared only towards P2P Payments, lest it cannibalizes the banks' golden goose, i.e. payment cards.
> same-day ACH is widely used, and again the delay allows more efficient netting.
Importantly, customer-initiated/"push" ACH is largely not a thing in the US, unlike in many other countries. This is what people unfamiliar with the US landscape often have a hard time understanding.
> A very important point is that debit cards offer consumer protections (chargebacks for unsatisfactory goods). FedNow, Zelle, wires, ACH do not and people have lost money by scams this way.
That's the crux of it: The US seems to be culturally unwilling to accept the risks (fraud) and rewards (practically free P2P and B2C payments) that come with a customer-initiated/push payment system.