If the recipient of a check wants assurance that there is actual money behind the check, they should demand a cashier's check for reasons I already iterated.
Receiving a fake cashier’s check, or the opposing party hacking into your bank and showing a transaction that will disappear?
Regardless of how unlikely the fake cashier’s check is, a fraudulent electrinic money transfer is still more unlikely. And the electronic transfer is cheaper (free). And less work for everyone.
As far as I know the only way to execute an immediately-settled electronic transfer is a wire transfer, which is inaccessible to lots of people and has an associated fee for nearly everyone else.
Zelle transactions are subject to reversion or cancellation ... for days?
Compare to, say, settlement cycles in SWIFT: https://www.swift.com/news-events/news/preparing-t1-global-i...
You can't just unilaterally reverse a Zelle payment any more than you can a SEPA transfer.
However there is possibly some new "real-time payment" feature of the ACH network that could be equivalent to wire settlement, but I'm not sure Zelle actually uses it.
There's also FedNow[2] but I don't know of any retail implementations yet.
And Zelle obviously has a lot of limitations, such as being for smaller amounts of money so not useful for down payments or such, I was referring to checks versus electronic payments as a concept in general, not the US’s specific implementation. Which there isn’t one, but due to political failure, not technical limitations seeing as how every other country has the capabilities.