It would be a lot cheaper and probably less risky for the safe deposit box to be numbers in an account like it is with fractional reserves, except the part wher

It would be a lot cheaper and probably less risky for the safe deposit box to be numbers in an account like it is with fractional reserves, except the part where they lend it out privately. Even better if those reserves can be kept at the central bank overnight to earn a bit of interest. I also can't do an ACH or wire transfer from a safe deposit box.