I recently visited a friend in Copenhagen and when I got to his place, a condo on the third floor, he mentioned that his kid was outside sleeping. I thought that he mentioned on the balcony and I thought "weird but ok". About half an hour later we left and I learnt that the kid wasn't on the balcony bit out, in the common garden of the building, where anyone could have just came in because the main gate was simply always wide open... I am not a parent yet and I don't want to be an helicopter parent, but that still kind of shocked me. Can't decide if in a good or bad way.
We had a similar bit of culture shock when we went to Copenhagen and saw parents leave their babies in strollers out in the cold while they ate or had coffee (baby was well wrapped and warm of course). That sort of thing would get the police called on you if you did it in the USA.