When you buy out-of-state the selling dealership will collect your state sales tax on the amount you paid on your behalf. When you go to register your car back in your state you will find that what you owe (state, county & city sales tax) will be less by this amount if your DMV rep explains it properly. So you're not paying CA tax at the time of delivery but they may require a certain amount of "state tax" at the time of delivery... they just failed to explain what tax you were paying and what was happening with that money.
This is how it works in every state. You pay tax for your city, county & state if they require it and NOT that of where you bought the car from unless it happens to be in the same city, county and sate but you don't pay twice.