Comfort and Convenience
Seating position is personal: some people prefer to sit upright and close to the wheel, others further back with arms extended. Height, leg length and years of habit all pull the preference in different directions.
Safety and Driver Assistance
A few minutes stationary is a sensible way to locate hazard lights, demisting and horn before setting off. Preparation of that sort belongs to the parking space rather than to a moving lane of traffic.
Multimedia and Connectivity
Keeping a phone charged on longer drives is a separate matter from playing music or taking calls. Where a charging point is available, the useful habit is connecting at the start rather than mid-journey.