NHTSA Car Safety Requirements Require US Carmakers To Design Cars That Are Safer For Those (IDIOTS?) Who Do Not Wear Seatbelts

According to US car makers, "NHTSA's requirement makes cars less safe for belted occupants, since protecting people without seat belts requires more powerful air bags and other changes."

European car makers are not bound by these requirements and design cars that provide good protection for unbelted occupants BUT which are tuned specifically to protect occupants that are doing what they're supposed to be doing.

I think that wearing or not wearing seatbelts should be mandatory for those younger than 18 years and voluntary for those 18 years old and older BUT cars should be designed with the assumption that all occupants are properly belted in.