Helmets for car occupants?

What a bizarre idea.  Or is it?  Many years ago, when I was walking to school, any friend passing by on a motorcycle or scooter could offer me a lift, and I would just hop on without a care. Then we had compulsory helmet-wearing, despite the best efforts of the then newly-formed Motorcycle Action Group. Now the busybodies are trying again to get helmet-wearing made compulsory for cyclists.  I thought it odd that the notion of helmets for car occupants never, ever, gets a mention so I consulted Dr Google to find out if being in a car makes you invulnerable to head injuries.  Surprise, surprise!  While motorcyclists, cyclists and pedestrians are particularly vulnerable, head injuries are still commonplace for those in a car that’s involved in a collision.  In the US, car crashes are the leading cause of fatal head trauma in young people.  Here in the UK, charities like Brake, Headway and the Acquired Brain Injury Forum are well aware that large numbers of car occupants suffer serious head injuries.  Because of the numbers involved, it’s arguable that pressure on the health service from this direction is greater than from motorcyclists, cyclists and pedestrians combined.  So why do we only hear about motorcyclists being prosecuted for not wearing helmets, or cyclists being told that the law needs changing to force them to wear helmets?  Simple: motorcyclists and cyclists are minorities that can be kicked around with impunity, whereas you can readily imagine what would happen to the re-election prospects of any government that tried to introduce compulsory wearing of helmets for those travelling in a car.