People who engineer the computers don't usually think about
security issues, but rather the convenience for the technicians
who will work on them in the future; I think its a holdover from
the days when smaller computers were for nerds like me only.
Back in ancient days, before my time, computes had their own
rooms, security, air conditioning, everything.* But once they
got small, everything about them was built upon hobbyist
principles. But the bank should have been security-minded; and
in your shoes, I would have equally walked out that door.