I know exactly what they do, and what the point of them is, and in all my years of driving, mostly on vehicles not only with no backup cameras or any backup beepers, but also with huge blindspots in the rear driving mostly trucks, knock on wood, I've yet to ever hit anything backing up because I'm paying attention when I'm going backwards. With a backup camera, I have an even higher sense of awareness for backing up, I REALLY don't need the stupid beeping. Justify the additional safety aspect till you're blue in the face, I get the point of it, and it drives me nuts more than it helps me out.
I don't have park assist, and I have 2 eyeballs, I don't backup without looking where I'm going. Some of the newer safety features are nice like the blind spot indicator system, or cross alert indication, because they indicate beyond my line of view. Other safety features are annoying and unnecessary for me, such as the annoying backup beeping when I'm looking in the mirrors and the backup camera seeing exactly what's behind me. It may as well start beeping at me every time I exceed the speed limit too.