Apparently you can establish financial independence with the right evidence, even in California, but they don’t make it easy. California does specify that you cannot establish independent residence unless you have also established financial independence.
http://registrar.berkeley.edu/Residency/establish.html
“Adult students cannot derive residence from a spouse or parents.” (■■■?)
http://registrar.berkeley.edu/Registrar/changes.html
“You may be considered “financially independent” if you: … f) is a single undergraduate student, and was not claimed by his or her parents or any other individual for the two years immediately preceding the request for resident classification, and demonstrates self-sufficiency for those two years and the current year.”