The problem is that California stopped building freeways in 1975 and we don't have much in the way of public transportation. Therefore people end up driving at freeway speeds in neighborhoods with children and pets.
An interesting example is highway 17 which is the only freeway between silicon valley and the beach. On a hot summer day the entire freeway is gridlocked. Beach goers believe they can get there faster if they drive through the streets of Los Gatos. This shuts down an entire town.
There are plenty of stories about how we dismantled public transportation after WW2. I am not sure how true they are so I won't repeat them. One thing that is true is that eminent domain has become much more costly in California making it difficult to rebuild public transportation after we dismantled it.
Here is an article on why we stopped building freeways: https://www.accessmagazine.org/fall-1993/why-california-stop...