I think the problem perhaps is that in house-owning countries, the apartments are usually cheaply built, or cheaply converted, so leak sound like sieves, becaus

I think the problem perhaps is that in house-owning countries, the apartments are usually cheaply built, or cheaply converted, so leak sound like sieves, because everybody who has any money wants to live in a suburb. In apartment-living countries, they put earth between the floors, and the walls are pretty heavy duty. So you don't really have that much noise pollution.