I've been getting better about wearing the belts, mostly because the newer cars nag you about it until you fasten them. I make it a point to always buckle up in the Corvette, now I find myself buckling up in both the Civics. The grandkids tell me to buckle up and also let me know if they aren't strapped in as well so the young ones are getting it.
Our Mustang and kit car have belts. The T-Bucket is not equipped at all and I'm not sure I'm going to - these cars are so light that I'm concerned about being in a rollover and would rather take my chances being thrown out of the car than being trapped in a belt while being smeared down the highway or crushed after going upside down. So far, more than 10,000 safe miles in that car although the T is just a notch safer than a motorcycle in the exposure department. As one poster said - calculated risks.
I had a '97 Ford Explorer that I parted out a while back. For grins, I mounted one of the airbags in a vise and set it off. I drew my own conclusions about airbags after that bit of fun.
Driving reasonably, defensively, and maintaining good situational awareness will considerably decrease your likelyhood of a collision.