Little kids don't observe common-sense safety measures, and can dart out behind a car before a parent even realizes what's happening. Also the cameras usually

Little kids don't observe common-sense safety measures, and can dart out behind a car before a parent even realizes what's happening. Also the cameras usually have fairly wide-angle lenses. In situations like backing out of a spot in a parking lot, the camera often can spot vehicles or pedestrians that you otherwise would not see if you were just looking out your rear window.