There is no such thing as 100% safe vehicle of any kind made by man. It is incumbent upon the users of them to use good judgment and due care in their operation and use. RVers as a group seem to be more careful than the general motoring public.
In several states seat belt usage is a primary offense (meaning one can be stopped and ticketed for not using them). I was stopped in LA on I-20 driving my father's little Class A. He just couldn't see that I had my belt on. You are not likely to be stopped if the folks in the front are using their belts. Whether I drive a school bus, Transit bus or an RV, I always try to remember that I have precious cargo aboard and drive accordingly.