If private schools are going to exist they should have a minimum curriculum actually enforced so that students attending them aren't put at a disadvantage.

For example, sex education should be required as part of health and human biology. Not it's own separate, needlessly controversial thing.

Many private schools are religious and refuse to teach certain topics, or replace them with nonsense and it hurts their students.

But also don't give them tax money. They rake it with their excessive tuition already.