Driving a car is a privilege, not a right. There is no constitutional right to drive a car so there is no privacy issue any more than other people can see in your car, including the police.But, an intrusion of our privacy is still an intrusion.
It is the same concept as full body scanning at airports. There is no constitutional right to fly. Air lines are private companies.
If you chose to fly, you consent to the rules governing flying the same as when you get a driver's license and drive, you are bound by the rules of safety, including not running red lights.
I do not want anyone running red lights or carrying bombs on planes.
OBTW, I am a lawyer.