On top of that, I guess it’s very, very far from trivial to spin up such a service even though it’s true the USPS has a nationwide physical presence. It might be fair to say it’s easier than starting from scratch, maybe, but the USPS has entrenched practices and infrastructure that might not easily extend to physical and digital security required to handle high volume finances at all.
Does having electronic accounts cover everyone? We seem to have a rapidly growing homeless population in the US, and many homeless people have real difficulties holding on to cell phones & documents long term, anything that would allow them to authenticate and/or use an electronic account.
If electronic accounts were the solution, I could also imagine the primary infrastructure being a phone app (maybe not entirely dissimilar from China’s WeChat). In-person cash transactions for deposits and withdrawals could perhaps be mostly handled by ATMs?