This makes perfect sense to me. If you plug your phone in to your car and give it permission to access all your shit, then it will access all your shit, and store it locally so that it doesn’t have to re-download all your shit every time. If you don’t want your car to do that, then don’t plug in your phone and give it permission to do that.
Having said that, it is terrifying how much of our personal data modern cars collect. We should be fighting that, but this specific case was not the way to do that.