Sure, postal banking [0] has been around forever. Could it be updated to the modern day and in the US? Of course! Why not? Because we apparently just can't have nice things.

It's a perfectly good idea that just doesn't have political traction in this era.

We could also have, you know, universal health care. Like any other normal country.

[0] https://en.wikipedia.org/wiki/Postal_savings_system