Comfort and Convenience
Seating preferences vary with height, leg length and driving habits, so a position that suits one person can feel wrong to another. Sharing a car usually means changing something before each trip.
Safety and Driver Assistance
Spending a few minutes finding the lights, wipers and demisting controls before a first journey leaves fewer distractions later. That is simplest while parked rather than in moving traffic.
Multimedia and Connectivity
Keeping a phone charged on a long drive is a separate need from playing music or handling calls, and a car may cover each of those through a different connection.