I hate the way 'lazy' mums and schoolchildren are to blame for traffic on the roads, and quieter roads during the school holidays are used as 'evidence' of this.
Roads are quieter during the school holidays because that is the time when far more working people who drive to work are likely to be away on their holidays too, is it not? 
And so what if people use the car to get to school instead of the bus? How is their commitment and timekeeping less important than anyone else's?
One adult getting to work by bus/train = one person, one fare, one journey to work, one journey back again.
Two siblings getting to school by bus with a mother and a baby sibling in tow = Four people, three bus fares, one journey there, one journey back home for mum and baby, another journey back again for mum and baby, and the final journey home for all four of them, plus a shitload of hassle and wasted time. And that's assuming there is even a suitable bus route or train station near enough to the final destination.
School is a commitment, just like a job. I see no earthly reason why children should be considered as second class citizens in this; less important or less entitled to get to school easily, safely, quickly and on time any less than someone with a job of work? 