This would benefit the poorest people in Britain the most – since they would get financial assistance, they could send their children to schools charging full fees without having to pay, and so would get the biggest boost to their education funding.
This is also more ethical than university fees as parents can afford to pay fees, unlike students who have no incomes. Furthermore, parents can judge the quality of a schools since they have finished school, unlike students who have never been to university and so cannot tell the difference between a good and bad course. It is much more sensible to let schools charge fees than universities.
It would create real choice for parents as this increased funding would allow more schools to open, with better facilities for parents to choose from. It would therefore also make it easier for parents to find a suitable school in their local area.