I will say this about car seats, alas it does not apply to motor homes. (I have a comment re; motor homes too though)
As a police dispatcher I've either seen or sent troopes to many accidents where a child was involved. Several of them the child was held in his or her mother's arms (In the early days) and though adults walked away with minor, if any injury it was the skill of the doctors that saved the child's life.
After Michigan's child restraint law went into effect I still sent many troopers to many accidents (or saw them myself) and in thiese in many cases the accident was so violent that the adults, in spite of seat belts, were killed.
The child, however, was not. Covered in blood, yes, but not his or hers.
One accident I personally saw, Compatc Pickup truck had rolled, Mom and Dad did not believe in seat belts, Junior was, of course, buckeled in, When I got there Mom was dead (Truck rolled over her and crushed her after she was thrown from the cab. Dad was hurting (Mostly road rash, what you get when you go sliding down the pavement on your face) junior... I think he may have needed a band aid or two (I've done worse damage shaving in the morning)
Now RV's. One tihng going for the child in a collision in an RV is physics. 22000 lbs of RV v/s 2200 (note less zero) car the RV won't stop as fast, Don't make much difference though if the other guy is 160,000 lbs of steel hauler or a bridge abutment.