I am from Canada, where such a thing is almost unheard of. Private school is considered a luxury.

This is a culture I'm very much unfamiliar with. Thank you.

And really, I've only ever seen rich kids with minor substance abuse problems get sent to private school.

That just tells me that you've never lived in a city with truly atrocious public schools like Detroit, Newark, or New Orleans.

In those cities, any caring family who can beg, scrape or borrow the funds sends their kids to private schools, including most middle class families, and many poor families (off a combination of scholarship money and extended family contributions).

In Miami there are also charter schools and magnet programs too. His school, costs $15k/year

http://www.belenjesuit.org/page.aspx?pid=614