Hy dantheman49-6400, the story I learned was that people smarter than the average bear determined it was safer to lock the drivers door from the inside, and then slide across the seat and out the passenger door which you can lock from the outside with a key. This means you must enter the locked truck from the safety of the sidewalk or the safe side of the road, and that you exited the truck onto the sidewalk or the safe side of the road, and in doing so were in less danger of injury, hope that helps.