The state I live in apparently has one of the highest seat belt usage rates (despite no rear seat belt enforcement for those 16+), which would explain why I almost never see people avoiding them. Sorting by usage in the Wikipedia table, I don't see much of a correlation between policy and the actual use except with primary vs. secondary enforcement, which would imply it's more cultural than not. That said, I agree that it's very disappointing that people don't understand the importance of wearing a seat belt when the cases are all around us showing that in almost every situation they are beneficial.
"Self-reported seatbelt use among adults in the United States increased steadily between 2002 and 2010, with the national prevalence reaching 87% in 2010. However, seatbelt use in states with secondary laws continues to lag behind that of states with primary laws. This lost opportunity has tremendous costs. NHTSA estimated that nearly 450 additional lives would have been saved, 12,000 nonfatal injuries prevented, and $1.6 billion in societal costs saved in 2009 alone if all states had primary laws."
http://www.sciencedirect.com/science/article/pii/S0022437512...
Random anecdote: I travel to India on a reasonably regular basis to visit family, and I'm inevitably the one person that insists on wearing a seat belt and gets called out on it. Before traffic laws were actually (sort of) enforced in the city I generally visit, front seat occupants never really wore them either in my experience. It boggles my mind that people would travel at 120 km/h on inconsistently paved roads with insane drivers on the road and no seat belt to hold them in place.
"Self-reported seatbelt use among adults in the United States increased steadily between 2002 and 2010, with the national prevalence reaching 87% in 2010. However, seatbelt use in states with secondary laws continues to lag behind that of states with primary laws. This lost opportunity has tremendous costs. NHTSA estimated that nearly 450 additional lives would have been saved, 12,000 nonfatal injuries prevented, and $1.6 billion in societal costs saved in 2009 alone if all states had primary laws." http://www.sciencedirect.com/science/article/pii/S0022437512...
Random anecdote: I travel to India on a reasonably regular basis to visit family, and I'm inevitably the one person that insists on wearing a seat belt and gets called out on it. Before traffic laws were actually (sort of) enforced in the city I generally visit, front seat occupants never really wore them either in my experience. It boggles my mind that people would travel at 120 km/h on inconsistently paved roads with insane drivers on the road and no seat belt to hold them in place.