Can you please elaborate what is so difficult to understand about the concept that when you drive fast and crash you get thrown out the windshield and possibly die? What does it mean to you that this understanding already fails?

It's a constant minor annoyance weighed against a fairly rare, hypothetical risk.

People ride motorcycles despite vastly higher death and injury rates than cars, cause it's fun. (I did for awhile and might start doing so again one day.)

I'm not disagreeing with you I don't think? I agree that it's a really stupid thing to not wear a seatbelt. I just think it's important to consider how to solve these problems without throwing up our hands and saying "people are irredeemably stupid" because that doesn't really do much good for anyone.

>Because the average person has a very bad understanding of risk and consequences?

When it comes to things that are defined by social consensus (like whether or not one should wear a seat-belt, or smoke indoors, etc) like the hypothetical "average person" is always correct by definition.