American walls do. As a rule, American residential construction is prefab housing; the exterior walls are chipboard with (usually) wood siding, sometimes brick veneer, the interior dividing walls are sheetrock. Floors are wooden, too, a soundproofing layer between the floorboards and joists is not standard. You could not get brick construction if you wanted to. Not too far from my apartment is a well-to-do part of town. Someone is building a new house next to the golf course there, and the half million dollars that that fellow paid for his new pile still gets him nothing better than chipboard and sheetrock. Apartment buildings are constructed in the same way. With the wrong neighbour, an American apartment can be a gigantic horrortrip.

The poor quality of construction in America goes a long way to explain the allure of suburban living. There is a wide air gap to the neighbours and you have little road noise on your cul-de-sac. It also explains the suspicion Americans have against proposals for high-density housing, they expect construction quality to be poor.