Looking from the outside I would guess this is one of the big reasons for the "missing middle" [1] (lack of medium-density housing) in most North American cities. It is simply not economically feasible to build a small to medium size multi-unit building if you need to include two stairwells, so all buildings are either single family houses or huge mega projects.
In my country the simple and cheap four-story walk-up condo building (with a single stair and no elevator) is the bread and butter medium density housing for the working class. You either have two or four units per floor, all opening to the stairwell with almost no space lost in corridors, it is simple and efficient. Alternatively for higher density there are higher versions with typically up to 12 floors with one or two elevators but still only one stairwell, so keeping the same efficiency.