It's not just that, either. US banks have been slowly working on faster payments system (RTP, run by Clearing House Payments Co since 2017) and then in late 2019 their regulator, the Federal Reserve, told them "hey, we're going to make a competitor to this new system."
There is some merit to the idea of Fed-operated system here, but, well, let's just say that investing money into a system only to end up competing with your regulator doesn't really help banks feel like they're in a stable regulatory environment where they'll be rewarded for doing the right thing and making investments in the future.