ACH takes days to weeks to clear anyway, especially if new sender or large amounts = untrusted. There is no real exception handling so you are given the amount on credit.

https://engineering.gusto.com/how-ach-works-a-developer-pers...

(From parent) > And the payee doesn’t need to share their bank info.

And this is a US concept where having the magic numbers lets you pull any amount you want, with no ability to have a "push only" number...

It does. The US banking system is still predicated on paper checks, however, and efforts to change that face considerable inertia. There have been posts on HN explaining how (insanely) it all works.