You see systematic discrimination as spending roughly the same amount on each child. I see systematic discrimination as spending disproportionately much more public money on some children at the cost of others. We both find systematic discrimination of public education funds as unethical, but draw different conclusions on who is being discriminated against. I don't see our difference of opinion as an ethical deficiency in either of our persons.
I disagree with the rest. Universal schooling is an important part of a health society. It is up to the government to provide adequate funding for its obligations. Systematically discriminating to ease budget constraints is not an ethical solution.