But your example is flawed as Rydabent pointed out. Your logic is assuming that rider b has never had an accident and thus with his experience and safety record he would be safer then rider a...duh! But that still doesn't mean that tomorrow rider b goes out and has a not at fault accident that gave him severe brain damage or death due to failure to strap on a helmet. Not all accidents are the riders fault, and that's another flaw in your logic, your assuming he's never going to crash because he's never going to be at fault, you left out the other guy entirely.