Comfort and Convenience
Cabin temperature is a good example: one person feels settled with cooler air moving steadily, another prefers warmth and little airflow. Height, clothing and where someone sits all shape that judgement, which is why agreement on a single setting is rarely automatic.
Safety and Driver Assistance
Taking a few minutes while parked to locate lights, wipers and demisting, and to set mirrors and seating, means those things are already sorted once the journey begins. Preparation of this kind is simply a sensible habit, and it costs little before setting off.