Not all banks support Zelle.
It's a 3rd party app.
And sure, there would have been no need for it to exist had the US government done its job 20+ years ago as opposed to waiting until the 2020s, but the reality is that most Americans have been able to instantly transfer money online using their bank for quite a few years now.
If you do not, then you should probably sign up for a free account at any of the multitude of online banks that do have the capabilities.
For example, at CIT Bank, which I easily opened a free online account, I have ACH limits of $250k outgoing and $500k incoming, PER DAY. All I had to do was enter my account #/routing # for my other bank accounts.
Zelle is a shitty middleman with ridiculously low transfer limits.
https://www.bankofamerica.com/online-banking/zelle-transfer-...
Zelle is just a payments network.
https://en.wikipedia.org/wiki/Zelle_(payment_service)
Also, as far as I understand, the mechanism of ACH prevents it from being instantaneous, requiring old school processes every night to reconcile and finalize transactions. ACH does not check if accounts have money in real time, it assumes it, and then deals with problems later, which is why transactions take days to finalize.
The biggest banks got together and created a new network for transfers, and charge all the smaller banks fees to access it?
It sounds like another method of crushing competition.
It sounds like the US government was asleep at the wheel and the big banks got together and did what they had to to enable US residents to be able to instantly send money to each other electronically.