If it’s SF I gotta know why there are so many cars there then.

Part of this will be people who simply have the habit of driving no matter what. A small part of that will be people who legitimately need a personal car even in a fairly pedestrian friendly area (eg, people with disabilities). However, a big part of the phenomenon you are observing is people who live in SF needing to leave it, and people who live outside SF needing to enter it. While SF itself may be pedestrian friendly (relative to the rest of the US at least), the bay area as a whole is still a cars-as-default space. So maybe you bought a house in the city proper and love living there, but your job (which you got after buying the house and which you must keep in order to pay the mortgage) is in a suburban office park. And you have many friends with homes in the suburbs who you like to visit. And you love travelling to the Sierras, but there is no good transit for this purpose. On the other hand, perhaps you live in the burbs, but work downtown - you could park at a more far-flung transit station and ride transit into the denser part of town, but due to the friction of transferring between modes, sitting in traffic for a few more minutes is a less painful experience.

The solution is simple: either charge more for public on-street parking and aggressively enforce parking laws with meter maids - or simply ban cars from streets/areas which are already pedestrian friendly. In either case, especially in a place like SF, you should also scale fines for breaking the law with the law-breaker's income/wealth.

Saying there isnt enough parking in SF is like saying that there isnt enough ice cream in SF. Sure, everyone will admit that they like it when it is presented to them - but the fact is that the government shouldnt be in the business of ensuring that there is a limitless supply of it at all times.