I've encountered the same thing in Germany, when I log in I use the branch number of where we opened the account? Why? Who gives a shit about that? I certainly don't. But the bank does, for some unfathomable reason.
For each way German banks are better than American ones, it seems like there's a way in which they're backwards or overly conservative.
Side-story: southern Italians who relocated to the industrialising North during the ‘Italian Economic Miracle’ of the 1950s to 1970s referred to the process as ‘emigrating’. Until it was looked down upon by more modern sensitivities, they were referred to as ‘immigrants’, and their offspring referred to as first- and second-generation immigrants.
It really is a rather static society, though now there’s a significant and constant flow of young graduates from the hideously unemployment-afflicted South towards the North, or abroad since the Great Stagnation set in about fifteen years ago.
In the US and Canada, you’ll have a home branch too. Usually it doesn’t come up in anything day-to-day.
State laws for one thing may apply to accounts opened in a particular state.
But if a bank merges or gets acquired, or fails, and some branches get sold/divested, and not necessarily to one party.
One could find themselves a customer of a bank that is no longer local to them.
Here’s a merger that had a divesture:
https://www.bauerfinancial.com/2019/12/09/its-truist-theres-...
I ask because in the UK, each bank branch has a six-digit "sort code", which others will need to know in addition to your account number to transfer you money. However, you can open an account at a branch and never step foot in that branch again afterwards, only ever using other branches. Account numbers are only unique for the same sort code.
This is at Deutsche Bank, by the way, not some podunk obscure bank.
Of course, if you do move and you want to apply for a new credit card, they will mail the card and paper work to any of the locations, so it's not that bad. And all of the banks in the group have an unified online banking system, no branch numbers needed. However, when I switched between the different banks, I had to get new login details for the online bank, which was kinda sucky.