The other problem in the Bay Area is that cars don't know how to merge and no one wants to let another driver in front of them. Packs of 5 or more cars driving

The other problem in the Bay Area is that cars don't know how to merge and no one wants to let another driver in front of them. Packs of 5 or more cars driving close to each other will try to merge in to the freeway with cars on the freeway, who also have little space between them. So eventually everyone needs to brake and it slows everyone else down. And turn signals are seen as a sign of weakness -- cars will actually speed up to close a gap when you signal.