If the place you are in is already built poorly, then the it is neither “very easily” or cheaply fixed.
There are tons of poorly built detached houses as well, that are also not easily or cheaply fixed, that is orthogonal to the debate between house or apartment.
Except you don’t need to soundproof your detached house. You can run and jump and yell all you want without bothering anyone.
If you live in a high quality house with large space between houses, maybe. Sound is very transmittable by air, if you are in the garden or open a windows there goes the sound insulation. There are tons of houses with ‘special cardboard’ as walls and not really that much distance laterally between the houses, so all the loud sounds will be heard. Again, if you build with bad quality, anything will be bad.
