I'm not big but I've had injuries which have hindered my mobility. Ever tried to get into a low subcompact when you can't bend as easily? The height of the seat, the height of the A-pillar/roof, the width of the door, and how far the door open, all massively affect getting into and out of a vehicle.
These are all reasonable cases to expect accommodation for! The part that I'm not convinced on is that said accommodation needs to take the form of an absurdly large SUV or pickup truck.
