Often, people over look the fact that not wearing a seat belt puts other people in your car, or in another person's car in danger.
My entire family is in the medical profession, and I can't tell you how many real life trauma videos (were the aftermath was shown) I have seen were unbuckled occupants in the back seat flew into the front seats, consequently killing both passenger and driver who WERE wearing seat belts and had dual front/side airbags deployed - at speeds of 35-50 mph. Or in head on collisions or T-Bones were the driver of one vehicle flies thew the windshield of their vehicle, threw the windshield or driver side window of the OTHER vehicle, consequently killing the driver of that car - again at speeds of 35-50 mph.
There is absolutely no logical explanation as to why people chose to drive without a seat belt. It should be a law in all states, enforced with penalties, because your actions no longer have consequences for yourself, but for others.