I use the back up cameras so I can see what is behind the center of the vehicle which is often a blind location.

We have all driven vehicles where the rear view mirrors, and even including the outside rear view mirrors, leave a very large area of 3'-4' behind and often from side to side that we simply can not see if there is anything back there or not. The back up cameras provide another view we may not be able to see any other way, a forth view that wouldn't otherwise be available. Even with that extra view, it would not be responsible to not still use caution.

For instance, the widest point on my 48 Plymouth coupe is the rear edge of the front doors, and the rear window is pretty high on the vehicle and its pretty narrow. The view through the the inside rear view and both outside rear view mirrors pretty much leave you guessing if there is anything behind you, or how far back it might be. That rear view is about the same as most E bodies, and several 70s models of B or C body cars as well, and even most step side pickups. The license plate back up camera view lets you at least see what is directly behind you. They are great for parking.

To me that is a pretty worth while $40 or even maybe a $100 investment.