Comfort and Convenience
A bag in the footwell on a shop run feels fine to some passengers, yet others want that space left clear, because clutter tolerance differs.
Safety and Driver Assistance
A second driver can sit with the car parked and learn which stalk works the indicators and which works the washers, so the two are not mixed up later.
Multimedia and Connectivity
A passenger waiting to collect someone may want a podcast. If listening is available, it is a different task from placing a call and from charging the handset.