Greetings,
I think, with regard to America, it's relatively easy: ensure that all education is measured through the same metric - exams.
Charter schools are defined as "private", as a result, the children attending them don't have to do the exams that those in public schools have to do. This is ridiculous - although they're managed privately, they are publicly-funded. They should have to meet the same standards, exam-wise, as public schools.
Equally, home-schooled children don't have to take any exams(!) - how does anyone know if they've been educated, never-mind actually meet the standard of a good education.
This means that parents (and cults) can use "home-schooling" as
a means of keeping control of children, and brainwash them.
This is the same sort of thing that occurs in abusive relationships, where the controller (abuser) doesn't want their partner working, then they don't want them to socialize with their friends, and finally they cut them off from their family. At this point they have gained total control of their partner (victim).
The use of home-schooling as an excuse to isolate children from others is a classic tactic of such controllers.
I realize that there are people who use home-schooling for other reasons - practical rather than ideological - but the only way to ensure that the children are being educated, and not abused, is to test them against state/national standard exams.
Only in this way can you have over-sight of both charter, and home, schools/ing.
Kindest regards,
James