They save lives, but not all lives.
After my accident there were several rollovers where the teens were thrown from the car, only to suffer minor cuts, bruises and a broken ankle. I often wonder if I would not have been wearing my belt if I would have been thrown and survived, or thrown and killed. As it stands, I was merely paralyzed with a broken neck.
I don't know if all accident victims wonder 'what if', but I do. I also know God has his plans and I probably would have ended up the way I am regardless. But I still don't understand.
nothin is absolute, but, your odds of living and avoiding serious injury are immeasurably increased by staying IN a car during an accident. having 4k-6- of steel around you protects you better than flying through the air on your own. a teen who walks away from an ejection is in the small, small minority of those ejected.