It's extraordinarily difficult, and expensive, to convert parking garage space to housing - the heights are different, it's not designed with the same egresses, the floor material is concrete.
It also affects what the ground floor of buildings looks like - you can't have ten ground floor pedestrian exits or bike parking in the courtyard if the courtyard is on the third floor.
It also affects what the ground floor of buildings looks like - you can't have ten ground floor pedestrian exits or bike parking in the courtyard if the courtyard is on the third floor.