I think that people are stupid and dangerous if they do not buckle up...I always buckle up. That said however, it is a person's choice, and I don't think that the government has the right to make something illegal because they think it is stupid (as long as it is not hurting OTHER people). If people lose their right of choice because others think that their actions are stupid or dangerous to themselves, then the government can outlaw anything they want and just say it is for your own good.
It is a parent's job to make sure their kid buckles up, and it is an adults choice to buckle up or not. If stupid people do not buckle up, then guess what? The world will soon be rid of stupid, dangerous people who could otherwise hurt innocents! Nature has a beautiful way of working everything out.

They should concentrate their efforts on stupid things people do that can and do hurt OTHERS! For instance, instituting the death penalty for drunk drivers. Now that would make the road safer, and promote safer lifestyle choices for most people. :)