Most people I know in San Francisco don't own cars and certainly don't make use of freeways as part of their commute. With high-density cities and good public transit, you really have much less need for cars.
Also, given that cars are inherently dangerous, cause environmental harm, and take up a lot of space, it seems like it's in the public interest to discourage car ownership/use.
San Francisco is just one part of the problem, the other part is Silicon Valley. In SV, housing is even more expensive than SF, and public transportation is dismal at best. Rush hour in the San Jose area rivals that of LA, NY, etc.
Most people I know in San Francisco don't own cars
You must not know a big cross section of people then. Maybe in the downtown core, but a trip across the city will show very little available street parking and most houses with garages filled with cars.
It's a small minority of the city that don't have cars.
Yeah, I certainly don't claim that the people I interact with are representative of San Francisco as a whole. From some article I found from a few years ago[1], the vast majority of new residents don't have cars, but overall about 30% of total residents don't have cars. Most of my coworkers don't live downtown, and they get to work using BART, Muni, bus, or bike. When they need to get somewhere not on public transit, they use Lyft or Uber. In both of the two places I've lived in SF so far, I roomed with two other people, and none of us wanted the parking space, so we rented it out to someone else.
My point is that in many cases, there exists a reasonable city design and style of living where car ownership feels unnecessary and is better seen as a luxury than a right. Certainly there are many situations where car ownership makes sense, but I worry that people are sometimes too attached to the idea of car ownership and either incorrectly view it as a necessity or assume that everyone else needs a car as well.
Also, given that cars are inherently dangerous, cause environmental harm, and take up a lot of space, it seems like it's in the public interest to discourage car ownership/use.