A second point is the VERY TYPICAL SCENE of mom and dad bicycling without helmets while junior and junioress are wearing helmets.

So stupid. If you believe in helmets, the first person to wear one should be the bread winner(s). His or her loss to the family and the impact of that loss (financial, parenting and otherwise) will be much more significant than one of the children. BUt to believe that helmets are good for kids and not for the parents is really stupid.