Objects in Camera Are Closer Than They Appear
A backup camera or rear-view camera helps you see the area behind your car when backing up. It should provide more visibility behind your car than you can get by simply turning your head. But still, many people don’t like to rely on it (not just your dad!).

Turning your head might hurt your neck, but people tend to trust their eyes more than a camera. Old habits die hard, as they say. And like someone commented on this: I always do this because in driving school the instructor would scold me if I used the camera for backing into a space.