It's been quite a few years since I've lived in the US so maybe I'm out of touch. But where I live you can send money instantly to anyone if you know their bank

It's been quite a few years since I've lived in the US so maybe I'm out of touch. But where I live you can send money instantly to anyone if you know their bank account number. You can do it online via your bank's website, via a mobile app, or at an ATM. Can't you do that in the US via the ACH system? I recall ACH was slow, taking a couple of days, but I don't recall if you could ACH money to other people or only between accounts you control.