Comfort and Convenience
Cabin temperature is the clearest example of differing preference: height, clothing and where someone sits all change how warm a seat feels. Agreeing one setting, or directing airflow away from a person, usually settles it.
Safety and Driver Assistance
Locating the hazard switch, demisting and lights before pulling away means fewer distractions once traffic demands attention. A few unhurried minutes in the driver's seat, especially in a car you rarely use, also allows mirrors to be set.
Multimedia and Connectivity
Phone battery is the usual concern on longer trips, because navigation drains it steadily. Where a charging point is available and reachable from the passenger side, someone else can keep the phone topped up during the journey.