I don’t know what houses you see that have garages but don’t have driveways long enough to park on. The drive up area of a multiunit can also allow emergency service access, often allowing full access to the perimeter of the building by using the sidewalks or lawns during emergencies.

As for stormwater it is very rare that it is detained underground or underneath the road, most developments have storm sewers that lead to a stormwater retention or detention pond and in some cases the sewers directly lead into creeks, lakes or empty land.