SF is an awful place to own a car if you don't have a parking garage; however, you lose out on regional mobility. Marin, Sonoma, Tahoe - so many monumental vistas are an easy drive from SF, but nearly impossible without a motor. (Bicycling gets you some of the way there, but it's still life at a different scale.)
The ultimate SF cheat code is to get a Vespa - the regional mobility of a car, but the ease of travel and parking of a bicycle. Traffic doesn't exist on a Vespa.
My point was slightly different. If you want to go skiing for the weekend, you either have to carpool or rent a car of course. But in NYC (or at least Manhattan/parts of Brooklyn), there's just a general assumption among your local friends, organizations putting together activities, etc. that neither you nor a lot of other people have cars.
By contrast, with a group of paddling friends, some of which live in Cambridge, everyone has a car and while we'll carpool where appropriate the (correct) assumption is everyone has a car for gatherings and activities.
The ultimate SF cheat code is to get a Vespa - the regional mobility of a car, but the ease of travel and parking of a bicycle. Traffic doesn't exist on a Vespa.