Comfort and Convenience
Cabin temperature is the classic point of disagreement: what one person calls pleasant, another finds stuffy or cold. Body size, clothing and where someone sits all shape that judgement, so an agreed setting is usually a compromise.
Safety and Driver Assistance
Sorting out mirrors, seat position, lights and wipers before setting off takes a moment while the car is stationary. Doing it then, rather than mid-journey with passengers talking, means fewer distractions to handle once the journey is under way.
Multimedia and Connectivity
On longer trips a phone's battery often runs down before arrival, which matters most when it is also the navigation device. If charging is available on board, passengers can usually manage it without the driver intervening.