There’s no reason for it to take place in San Francisco ~ more assertive driving by ordinary commuters would take care of that problem. I used my own local situation as an example. The bicyclists and pedestrians are never given the slightest opportunity to get the upper hand in traffic around here.
There is no reason for it to take place in SF. However, it does and they very militant.
They will kick your car, through something convenient at it, bump it with their bikes and even body.
They love to feign they were attacked and the driver is usually in the minor position, ticketed or arrested, because they have “Plenty of Witnesses”.
It’s very unnerving to be in it and I had a car get scraped as driving out of the city. I thought I had made it but, maybe 50 yards from the 4th street entrance to 101 I heard a noise and the fool that was on the bike turned his head, started laughing and then just kept on going.
So, I avoid the city on Fridays.