Even the motorcycle helmet laws didn’t start to to into effect until the 80s/90s. that was about when airbags started getting added to cars so they were roughly

Even the motorcycle helmet laws didn’t start to to into effect until the 80s/90s. that was about when airbags started getting added to cars so they were roughly parallel efforts along slightly different lines. Essentially the car becomes the helmet and does a more complete job on the whole body than just the helmet on the motorcyclist.