his thinking is that a driver seeing someone without a helmet will stay farther away...
imo , another point is that helmets, just like on motorcycles, can interfere with hearing and sight and manuverability...maybe just enough so you don't catch the speeding car trying to get around you....
as with all our modern culture, we hold certain beliefs as "sacred" and not to be questioned, ala global warming, ala red meat, ala carbs, gluten,fatty oils, etc...
Ask Gary Busey if he should have worn a helmet when he crashed on a motorcycle in 1988.
http://www.people.com/people/article/0,,20120285,00.html
Bicycle or motorcycle you should wear a helmet. You are on 2 wheels and a few pebbles can throw you off the bike.
http://i157.photobucket.com/albums/t57/Thomzilla/FarK/busey_two.jpg