That's not that silly at all!
Quite sensible in fact, and also quite common here where I live in Germany.
And you don't have to ask your neighbour when you want to get access to your car - you just have to turn a switch and the ramp lowers/raises to give access to your car.
This means that you can get more cars into the same relative space!!
Also, if I remember correctly, out here in Germany there is a rule that parking provisions must be provided for any new build houses or industrial sites and many of these are underground garages (Tiefgarge in Gerryspeak). This means that there are a lot less cars parked on the street making it easier to find parking spots when needed, reduces car cime (as the underground gargae is usually secure), and makes the whole area look better.