I agree, there are waaaaaay too many parking lots in SF. If you covered every parking lot in the city with a 4 story multi-use building, what impact would that have?
You'd make it impossible for people to come into the city to work and eat? Or even live there?
I forgot, "with at least one level of underground parking" so there's no net loss in parking spaces
That's incredibly expensive to build.
The ROI on the buildings wouldn't justify it?
It's not. And it is a common practice (or even required) in lots of cities with tight space (e.g. Barcelona).
Yeah, cities that are not in the active earthquake zone lovingly called The Ring of Fire. Remember, the approach to the Golden Gate Bridge cost 1 million per foot of road up to it.
Puzzle parking systems[1] can make it quite affordable.