Dear God! I've never seen kids unrestrained in cars, and I'd be taking the license plate number and ringing the police if I did! That's utterly horrifying to contemplate. Even if there were a crash at 50kmh, say, you've still got a child flying at 50kmh until he or she hits something solid- either the interior of the car or the road. And it's faster than it feels.
I'm just shaking my head at the thought...