That's true, but it doesn't change the fact that head injuries are one of the most common injuries, and the most common cause of death, in car accidents.
No matter how you look at it, the stats prove that you are as much at risk of head injury in a car, as when you ski.
Nobody can open their mind and understand the car analogy because it's just not "normal" to wear a helmet in a car. And people accept what is normal, sometimes without looking at the whole picture. Lots of kids on here have been wearing helmets since they started skiing, so the idea of going skiing without one seems crazy. They automatically assume that they should call out anyone who skis without a helmet.
Some of us grew up skiing without helmets, in a time when nobody wore them. So for us, a lecture about wearing helmets to go skiing seems about as ridiculous as it would be to get lectured about putting on a helmet in a car. If you break it down, both examples are equally safety consious ideas, however the ski hill one is becoming common, so it simply seems like a lot more reasonable thing to expect.
It's a matter of safety, sure. But it's also a matter of brainwashing, bandwagoning, and societal pressures. 15 years ago people would have laughed at you for wearing a helmet for everyday skiing. The risk of cracking your head open on a tree or lift tower or rock hasn't changed, it's perceptions that have changed.
If societal pressures got people to start wearing helmets while driving, after a while everybody would claim that it was stupid to drive without one. They could certainly make the same type of statements that skiers make now about how they "got in a crash and their helmet saved their life", "know people who have died from head injuries", etc.
Most kids on here probably started wearing a helmet not because of their own safety concerns, but because of societal pressure in the form of their parents making them wear helmets when they learned to ski.
Why I bother with this subject, I'm not sure. I'm not trying to discourage helmet use at all, just trying to encourage a little open mindedness... (and yeah I see the pun potential there).