Part of what sucks about wrecks is that mechanical parts don't necessarily continue working as designed; actually, it's a real problem with mechanical parts in general. If I had to weigh the small likelihood a seatbelt that wouldn't unlatch would trap me in a burning or sinking vehicle, or being crushed beneath one from which I would've been thrown free if unrestrained, against the also small possibility of injuring someone by hitting them in a crash, I'd pick the last one unless they made an insisted I wear the belt. If they don't think their risk is large enough to demand I wear the seatbelt or get out I won't volunteer to accept other risks I consider greater just to protect people who don't value it much more than I (if at all). What if we ALL think we're safer without seatbelts than with; should I strap myself anyway to provide them protection in which none of us has much faith?