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

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.