If it were the case that people bore the full cost of their stupidity, then I would have little problem with people not using seat belts, or disabling ABS, or whatever; the problem is that there is a societal cost for all of these: through increased LEO costs, insurance costs, healthcare costs, lost productivity, etc. The big problem is where do you stop, at least with rear view cameras, the cost is relatively modest when designed into a car.
(For a much more expensive mandate, look at mandated child booster seats - the evidence is not as compelling as the govt would like you to think, and the cost is substantial, especially as 4 different designs, related to child age are mandated. The studies with a high benefit - up to 28% reduction in death rate - are based on all seats correctly fitted. Other studies based on "real life" scenarios don't always find a benefit, because up to 76% of child booster seats are, in reality, "seriously misused". It also conveniently skirts the issue that the #1 risk factor for a child being injured in a car wreck is not being seat belted at all; and #2 is a drunk driver. Just to be clear, I'm not saying that the mandate is wrong, but the costs are higher and the benefits lower than many people would have you believe)
In terms of the rear view cameras, in most vehicles, this could be addressed with better driver training - the vast majority of back-over deaths are avoidable, because reversing could have been avoided. My Dad always used to tell me, "Never park so that you have to reverse out, because you never know when the Russians might come". Whether he was being funny, I don't know.
But my driving instructor, and also my advanced instructor when I did advanced driver training said the same thing: Never reverse, unless you have just driven over or past the spot you are reversing into; that's the only way you'll know for sure that there's nothing there. With a little forethought, this is almost always possible. For example, if you don't have space to turn you car in your driveway, reverse in and drive out. You'll have got a clear view of the driveway as you drive past, so you can back in with confidence. Then when it comes to drive away, you can immediately see where you are going.
However, as many here already believe, many drivers simply have never be taught properly, or are too lazy to think things through properly; and we all pay the cost for that.