Whether or not kids around here wear a helmet seems to totally depend on the socio-economic make up of the community. I have noticed this on my drive home from work, which goes through 4 towns.

Working class communities, not necessarily low income: maybe really young kids (less than 8) wear them
hardly any adults wear them

middle class, mix of blue collar and white collar: a little bit better than the above, but I rarely see an older kid or teen wearing a helmet

mostly professional communities: the kids all wear them, but when parents ride with them, the parents don't! (unless they are "cyclists")
About 5 years ago, the police department in the town I teach in gave any student who wanted one, a free helmet. We found some of them thrown on the parking lot. I rarely see any kids wearing them when they ride to school. A few have them hanging from their handlebars. When I ride to school, I leave my helmet prominently hanging from the drop bar of my bike.