Congress asked the NHTSA to put together a report on electronic measures available in vehicles to help prevent fatalities from people being backed over. The NHTSA doesn't have exact stats on how many people are killed in these kinds of accidents because they mostly happen on private property. However, the agency does have a clear take on what it thinks of reversing cameras: they are "expensive, unreliable, and [give] drivers a false sense of security."
Some commentators have taken that to mean that there is something wrong with reversing cameras, in columns with titles like "Rear-View Cameras Not Foolproof." To put it simply: nothing is foolproof. True, there are rear view camera systems that don't provide much field-of-view or no nighttime visibility. And the gigantic backsides of some SUV's can make it difficult to get everything in the rather small screen used for the navi. Nevertheless, rear-view cameras are meant to be an aid to sound driving, not a preventive that can assure you never run over anyone when you reverse as long as you're looking at the screen.
The NHTSA is working on getting better numbers, but in the mean time it "plans to work to improve the use of detection systems to potentially help alert drivers to backovers."