Even with those, decent side mirrors and the ability to be able to back up using them precludes the need for expensive technology. Americans have become effete idiots. I was taught how to back my vehicle using only the mirrors, which I still do very often to this day. The other trick is to open the driver's door and look back! Used that technique just last night backing my Jeep into my driveway, I learned that from my dad (dates from the days when cars didn't always have passenger side mirrors, but can be useful even when they're present.). Funny story: My mother tried it once, and almost fell out!

As for tykes and bikes, checking behind the vehicle before getting into it coupled with a modicum of SA prevents those kinds of tragedies. But Americans are too busy with their fucking smartphones to be bothered with anything resembling correct vehicle operating techniques. So our OverLords felt compelled to be perceived as "doing something about it".
Just to illustrate how stupid most drivers apparently are these days: I had a new engine put in the old MBZ a few years ago. It shouldn't have needed one that soon, but it did, blah, blah, blah. Anyway, there was a problem with the throttle linkage and it got stuck with the car accelerating with no control from the pedal. While completely NOT desirable behavior in a motor vehicle, I was able to control it and safely pull off using a combination of the gearshift's neutral feature, limited braking, and the ignition key! Complete common sense to me, but my mechanic (after I chewed his ass...) expressed surprise/admiration that I was able to control the car! The only thing surprising to me was that he was surprised!
Another one: Ran over a screwdriver and got a horrid bump, bump, bump from a rear tire. Pulled off, coincidentally right by a road crew. They felt compelled to tell me that they weren't allowed to assist me - that's fine, don't need help anyway. I didn't at first know if it was a flat or if I'd lost a rear halfshaft. The guy asked me "What are you going to do?" like it was something horrid. "Easy. If its a flat tire, I'm going to change it and be on my way. If I've lost a halfshaft, I'll call a tow truck." I guess most/many people are helpless in situations like this? Anyway, it was a flat so I changed it.
Hell, I even had someone express surprise that it was possible to fix a bathroom fart fan by replacing the motor when the bearings wear out - much less that I was up on a ladder doing it. Its just fucking basic shit - I don't get it! That's why I bitch about effete (dare I say "pussified"?) Americans.