[tdj]

The building I live in in Berlin, 1910-ish construction with two more wings in the courtyard, everything accessible through the front gate - it has the same principle implemented with a timer and a button. I thought it's a bit odd, but made some sense after a while.

During the day, the front gate can be opened from the outside with just pushing a button that unlocks the door. At night (from 20 or 21 or so), the button stops working, you need the key. It can be opened at any time from the inside without keys. So it's more or less implementing the same protocol, but electro-mechanically, so there is no need for the trick with pulling the key inward.

[quelltext]

I might be misunderstanding the old school original situation, but your modern setup does not enforce/encourage that the door is closed. Even an automatic closing mechanism could be blocked by something.

With the Berlin key if you want to get your key (ostensibly you do and certainly don't want someone else to take it) you have to close the door. Of course you can still leave it propped open but unlike in your modern setup you actually have some stake in making sure it is closed.