look, no seatbelts!

Why on earth do people still refuse to wear seatbelts? Why on earth do people still think that they don't need to wear seatbelts when riding in the back seat?

Is it because they have never seen what happens to their bodies when the car they travelling in crashes and suddendly stops? Don't they know that their bodies will continue to travel in the same direction and at the same speed they were moving at just before the crash?

Don't they know that by not wearing a seatbelt they will die and/or injure themselves and others in the car?

It just drives me nuts whenever I have to remind someone to buckle up, or even argue that they have to put on their seatbelts or I won't start the car.