Having said that this is not a phenomenon unique to Switzerland. The majority of properties I have lived in all over Europe have required the use if a key to lock/unlock the door from the inside.
I also have put a little hook on the back of my door to hang my keys up mostly to stop small one unlocking the door, so the key is handy but not in the lock.
So in a fire, the first person would need to actually unlock the front door to get out. And there are no regulations on smoke detectors here, unlike say the UK in rented properties.
However, maybe people are just less likely to burn down their apartments here as I don't see any news/issues with the above being reported.
That way a second person can unlock the door from the outside, and your key is still in position, for emergencies, and with a small push is ready to turn and unlock.
...... and shouldn't the thread title be 'Strange Swiss Locks '
Please note carefully.... it seems that nobody has told you...
You take your key inside your apartment and lock the door on the inside.
Then you pull the key out a few millimeters, so the key is not out of the lock.
Anyone can now enter your apartment with a correct key.
If you need to leave the apartment, push the key into the lock and turn the key.
It was Bunderat Gnäggi which made this system mandatory in all newly built houses since 1966. It was he very first decree as a new Bundesrat. He second decree was to introduce his wifes invetion, the zippered turtelneck, to the Swiss army. To this date the zippered turtelneck is known in Switzerland as a Miss Gnägi. 1987 the then newly appointed Minister of Defence Adolf Ogi made the Swiss locking mechanism mendatory for all houses which were not converted yet. Knowbody knew exactly why.
But the whole truth and reason became evident during 1989 Fichenaffair. There was a secret meeting during the 1972 Winter olympics in Sapporo. Adolf Ogi, officialy head of the Swiss Ski team, was the Swiss delegative. The people addenting the secret meeting are wiedely known as the "Jiangshi-Circle", or in Swiss, as the "Totemügerli-Group".
The "Totemügerlis", you may know in English as "Zombie". Are very deep in the Swiss culture. Most houses built before 1966 had a Herrgottswinkel which could succefully prevent any Zombie outbreak in the house. Houses built after 1966 were carelessly built by immigrant construction workers which did not know the Swiss rules and customs. They simply forgot to built one. Many Swiss did not know that they lived in houses without a Herrgottswinkel. A new method had to be found to stop a Zombie outbreak. The solution was the lock that cannot be opened from the inside without the key. But it was highly secret to not scare the population, specially the growing expat community.
Now you know and hopefully you will remember during the upcoming Zombie apocalypse.