Not to mention, having a grass lawn in the Bay Area is a major social taboo due to water conservationism. You get more props paving than planting in my neighborhood (as long as you pave expensively).
Pavement vs Lawn is a bit of a false dilemma, though. Nobody in SurfRider's "plant don't pave" campaign is advocating lawns. In fact, they advocate against lawns. There are low (or no) water, drought resistant, often native plants that will preserve the soil filter, which is crucial for a lot of reasons (storm overflows, sewage bottlenecks, pollution from runoff into the bay and ocean).
Also, pave-overs are illegal in San Francisco - the problem is that the law is generally unenforced. Enforcement is complaint driven, and there's a huge backlog.
They advocate against lawns, and you can't park on typical "native" gardens (typically a lot of dirt, and some scrub brush), thus you are left with paving as the parking friendly eco-acceptable option. Or astroturf, but not sure how much better that drains than concrete.
