Sorry Grumpyengraver, but I really cannot believe or agree with your statement here. Only a very tiny proportion of casualties have suffered worse injuries through wearing a seatbelt.
There will always be those "rebellious" and "non-conformist" types who will find a few odd examples to back up their theories, but there are also several ex fire & rescue members on here who have seen it all at first-hand on numerous occasions and over many years.
I was in the fire brigade for a few years before the wearing of seatbelts became compulsory, and for many years afterwards, so I saw the difference that seatbelts made to the types and extent of injuries sustained by the casualties. I can't remember the number of road accidents that I attended over the years, but I was usually based at stations with specialist rescue vehicles, so it must be in the thousands.
I certainly have no doubts whatsoever about the huge positive difference that seatbelts make when used correctly, and I cannot take seriously anyones' advice about not wearing them!
And with respect, in almost all cases the casualties will have been extracted from their vehicles and be en-route to hospital long before a recovery vehicle will have been allowed anywhere near the scene.