I think you underestimate the extent to which parents can influence their children's behavour.
Often when kids skip school, its because of permissiveness attitudes from their parents. Many parents are permissive to the extent that they will allow their children to do irresponsible things which are against their long term interests merely to 'keep the peace'.
It must also be stressed that the docking of several week's worth of benefits is only a last option, to be taken if decision makers are persuaded that the parents are not doing enough top ensure their kids go to school.
You emphasise the fact that some families need welfare in order to survive. It is precisely for this reason that they will ensure that the kids go to school if their welfare is conditional upon it.
Commenting by HaloScan
