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.