Comfort and Convenience
Preferred cabin temperature differs widely. A passenger sitting still tends to feel cooler than the driver, and clothing, time of day and personal circulation all shift where someone sets the dial.
Safety and Driver Assistance
A few minutes parked is the easiest time to set the mirrors and seat and to see where the hazard switch sits. Adjustments made while moving take attention away from the road.
Multimedia and Connectivity
Hands-free calling is a distinct function from music playback. It relies on the phone being recognised when the car starts; if that has to be set up again each trip, callers wait.