This is very much my experience too. The difference between stout, newer buildings and old tenements are night and day. I used to live in a place made of massive thick concrete slabs with airgaps, and the only time you could hear neighbours was when somebody was using a drill, or on occasion, one neighbour singing in the shower so it travelled along the water pipes.
Other places, you can follow conversations through the wall if you're attentive and they're raising their voices.
Well, the issue is that it's difficult to know beforehand how good the soundproofing is. Even if you go to visit and it's quiet, is it because the neighbors are away or simply considerate? What happens when new ones move in?
I used to think living in a new building would be insurance enough. According to a colleague who lives in an apartment built in the 2010s, it's not.
For reference, this is in Paris, where there were laws passed in the 2000s supposed to enforce soundproofing in new developments.
Other places, you can follow conversations through the wall if you're attentive and they're raising their voices.