Consider that cities in N. America either have homes with large lots or condos with maximum 2 bedrooms (the price for 3 bedrooms or more scale non-linearly). Therefore it is very difficult to have a family of 4+ in an apartment.
The homes with large lots create areas with too low density which cause our transportation woes (long commutes, highways, infeasibility of public transport).
The 2 bedroom condo building are also often high-rises, which are also terrible (density is too high, making transportation near the building very difficult - just see the jams caused by people getting out of the high rise in the morning).
A more sensible, IMHO, is to have apartment blocks no taller than 8 stories with a good mix of 1, 2, and three bedroom units. These are found in poorer developed countries where the middle class could not necessarily afford a car, never mind two (my family in BsAs, for example in a 100 m^2, three bedroom apt)