I reckon those blokes are being a bit hard on you Bob, even though I don't have a reversing camera on my Ford Ranger work truck, I'd really like one, because there isn't a human alive who can see what's happening directly behind the tailgate area of this sort of vehicle, no matter how many mirrors he's got, unless it's a fricking periscope!
The Ranger has the reversing sensor beeper thingy which is much more trouble than it's worth, as it will beep like crazy if I'm reversing in my narraw driveway, yet won't beep at all if I'm backing up to a large glass surface (like a shop window, for instance) as the sonar waves travel straight thru the glass, closely followed by my towbar.
It's that "Boy who cried wolf" thing, after awhile I switch off and ignore it, whereas with a camera, I can do something that the human eye is incapable of, seeing thru a solid mass.
It cracks me up when I read posts starting with "I'm 400 years old, and I don't need no stinkin' unnecessary technology, blah blah blah", all typed on what is probably the pinnacle of unnecessary technology, the home computer................. Cheers, Terry.