Use or legislation of helmets while driving a car and walking would also almost certainly reduce head injuries. It's far from a sufficient argument for legislation.
Head injuries in car accidents are very uncommon, and the same with pedestrians. Pedestrians aren't likely to hit their heads on concrete at speeds well beyond that which the human body was designed for. Car accident victims don't have hard surfaces to hit their heads on in cars, and instead get other injuries. That's why seat belts are required by law in most jurisdictions, and also why airbags are mandated in all new vehicles.
Are you trying to argue against seat belts and airbags now? Are you going to claim that you're safer being thrown clear?
