I suppose this is now superseded by modern locks, but this is a great example of solving a problem with technology that would otherwise be left up to human beha

I suppose this is now superseded by modern locks, but this is a great example of solving a problem with technology that would otherwise be left up to human behavior. You could ask people to please make sure to lock the door, but there would always be people who would forget, or just not care enough to bother.