>> error prone humans to grant access to places. locks have been a thing for a milenia Except that a friendly smile and bit of eye contact can often prove enou

>> error prone humans to grant access to places. locks have been a thing for a milenia Except that a friendly smile and bit of eye contact can often prove enough to slip in behind after someone else opens a door. I know of buildings with claustrophobically small turnstile doors specifically to address this problem.