I assume it's state rented in (and therefor all cars rented in CA have different laws, liability is cheaper b/c they r not mandated to give minimum coverage. no matter what state the car is registered in)
liability is not cheaper in CA at least from Hertz, it's 13.95/day while in NY it's 12.95/day and other states that I have rented in, (NJ and IL) it's also 13.95/day
and yes, it goes by what state you rent the car in regardless of what state the car is registered in, they usually make the contract before they even assign a vehicle