1) congestion - any bike rider in Sydney is insane. It would be a miracle if a child was not hit by a car. 2) social - it's easier to catch the same bus/train with friends 3) distance - many parents insist on a certain school or not a certain school. With school choice, proximity is a minor factor. 4) princess - It's too hot/cold/windy/wet or they are tired.
population growth and parenting are the main factors.
i was the odd one riding to school as my neighbours bussed. The school bike racks were a tenth full at most then. It is slowly getting worse.
