I am not dumb enough to think that my medical insurance would pay the entire price of a major brain injury rehab (although my insurance pretty much pays for everything without questioning. And I mean some pretty expensive stuff, no referrals, etc). I only brought up the health insurance aspect because medical costs and not wearing a helmet are related. Also, with the advent of mandatory, state sponsored health insurance in MA (for those who don't have it through work), people are saying the same thing that they say about helmets and seatbelts: "The government should not tell me I have to..."
Last year my son had the norovirus. He was really sick and used his mandated state sponsored health plan (he works for a company with less than 10 people). His girlfriend, who had no insurance, because she is too cheap to pay the small premium for her income level, went to the emergency room and got "free care." Who do you think paid for that?