Comfort and Convenience
People differ in the temperature they find pleasant, so the setting one passenger chooses often feels too warm or too cool to someone sitting alongside. Shared cabins usually settle on a compromise.
Safety and Driver Assistance
Drivers who check the mirror and seat position before setting off are not interrupted by that adjustment later. The same applies to a car that is new or borrowed, where habits from another vehicle rarely transfer.
Multimedia and Connectivity
Where hands-free calling is available, it depends on the car picking up the voice and playing it back through the speakers, a different requirement from streaming music or keeping the handset powered.