in cities where real estate is expensive and a premium, which pretty much is all metro cities in this world, this doesn't even tackle the real issue of the cost of paying for the space to store these cars. regardless of installing a solar panel strapped to a car lift, shopping centres, transit hubs, method of addressing the issue of parking space is by paying for space (also going up is't free or unrestricted in most jurisdictions).
I see your point but there is still usable space going up in many places. In NYC for example, many buildings have garages with open air space that could be used to provide more parking. The cost of the space doesn't change whether you are parking 1 car there or stacking up. Might as well utilize the space to give more cars access to parking as opposed to just using for a single vehicle.