I'm not sure but I think airbags do detonate on most cars, regardless of the seat belt status. It would be too complicated or unreliable to couple the two systems.
However: an airbag isn't very effective (and could even be dangerous) without the seat belt, so manufacturers in Europe aren't really required to worry about the safety without seat belts. Effectively the safety regulations say: those with no seat belts are idiots breaking the law and it's not your job to worry about the safety those people. Which is completely sensible.
I think optional seat belt laws as found in some parts of the US can make some sense there (owing a lot to the fact that there is no single payer healthcare...) BUT the reasonable thing to do would be to not force car manufacturers to make cars less safe for those who do wear seat belts.
With regards to your first point, they do detonate. It's a question of how.
The main difference is the force with which they go off. In Europe, it's assumed you're wearing a seatbelt, so the force is less, which results in a lower likelihood of injury, compared to a US airbag. Personally, I prefer the European model - wear a seatbelt and you'll be fine, don't and it's on you.
Personally, I prefer the European model - wear a seatbelt and you'll be fine, don't and it's on you.
The other way around is kind of insane - you increase the risk for everybody who is using their safety equipment properly, for the benefit of those who can't be bothered.
> I think optional seat belt laws as found in some parts of the US can make some sense there (owing a lot to the fact that there is no single payer healthcare...)
Wat? So because the taxpayer isn't directly picking up the healthcare bill, it's somehow okay to double serious crash-related injuries and deaths[1]?
It's an age-old debate of "is it ok to (risk) hurting yourself?".
Obviously car crashes and other injuries/deaths come at high cost to society even in the case of privatized health insurances, but the cost is at least indirect rather than direct. It's probably even true that the majority of the cost is indirect, and not related to healthcare.
That said, not having a seat belt/helmet law is... well, stupid.
It's pretty direct unless you have a private ambulance. Otherwise it's tying up a valuable shared resource that could be used to save others whose life is in danger for reasons other than own stupidity.
In the case of seatbelts I think there is more than only thyself. You might be able to control the vehicle better post-crash, preventing injury to bystanders or passengers.
However: an airbag isn't very effective (and could even be dangerous) without the seat belt, so manufacturers in Europe aren't really required to worry about the safety without seat belts. Effectively the safety regulations say: those with no seat belts are idiots breaking the law and it's not your job to worry about the safety those people. Which is completely sensible.
I think optional seat belt laws as found in some parts of the US can make some sense there (owing a lot to the fact that there is no single payer healthcare...) BUT the reasonable thing to do would be to not force car manufacturers to make cars less safe for those who do wear seat belts.