Give me a break. Who is going to let the guy lay in the street and bleed to death. More importantly, who makes that decision, the cops, an EMT. How can they know wearing a helmet would have prevented the injury? "Oh Mr. Huey, I see you weren't wearing a helmet, I am afraid we will not be able to transport you to the hospital." Insurance companies may be able to do it because they have a contract that covers payment for medical procedures. When and where will a motorcycle rider be required to sign such a contract with the federal or state government. Everyone gets emergency treatment in this country. That is the way it should be. It is illegal to deny emergency medical treatment. Since I doubt you are arguing people should be left to die in the street, then we are talking about who pays. Either the hospital does it for free, or discounts the treatment below its costs, or the government pays. Either way we pay through taxes or costs past through to the other consumers that do pay. It is economics. Nothing is free. We pay in the end. One thing that my state has done is say that if you were not wearing a helmet, even on a bicycle, and a helmet would have prevented your injuries, you can not sue for damages arising out of that accident. In that case the injured guy gets emergency care but can not "profit" from his injuries with a large jury verdict.Rather than force me to change my actions (for better or worse), why don't we just say: "If you get in a wreck and you weren't doing the proper things to care for yourself (seatbelt/helmet/whatever), then the State is not going to pay for your healthcare."
Insurance companies do the same thing. If you don't follow their rules, then you are breaching your end of the contract and they will not pay.