businesses do leave california - people who more salaried jobs have left california. California has tax the shit out of the working class so expertly that the only a third of the people in the state pay income taxes.
It's one piece of the puzzle not the entire thing. There are pros and cons for consideration, nice things like weather and the ocean and the mountains that offset a lot of negatives. Try raising taxes to 99% and see how many businesses and people hang around. I don't care how wonderful the weather is, you put on a truly crushing level of taxation and cally will be empty of people who work for a living. I bet if you took California's taxes and regulation and applied it to a state with less to offer (such as Minnesota), you'd see a bigger impact.
Moving is costly, so most businesses will try to rationalize "hanging in"... at some point, they'll conclude they "have" to move.
So obviously these taxes do not seem to hurt them. They can pay these huge taxes and still live like kings. Just being a contrarian.
Most middle/upper class Kalis are still in love with the dream and cannot see the reality. Therefore just keep steadily increasing taxes and fines and maintain the illusion. The trick is to do it slowly and steadily and no one will leave. (frog in the pot theory)