When I'm in a parking lot and flanked by two SUVs then that's then the camera is invaluable! I can't see shit like that, but the camera with a wide angle on the back of the car can show cars coming as soon as I reverse up just a bit to poke the back end out.

Reversing cameras are certainly not the only tool to use when checking, but it's worth noting that kids under 5 (and especially around 2-3) get squashed at a much higher rate than kids tall enough to be seen out the rear window. I highly recommend glancing at the camera even if you're not trusting it.