This is just plain wrong, I am Brazilian and my mother is a teacher in São Paulo state public schools and the situation is horrible, what you see overseas are the high school grads that went to private schools in Brazil, the average citizen can not afford to go to school overseas even if they qualify (and they don't because they do not speak any foreign language) because some costs are not covered (visas for example).
What you are seeing is just the upper middle class latin americans leaving their crappy country for something better, they are the ones that can afford decent education. The situation for the ones that stay is really, really bad. Most public high school students would fail a basic reading test, in fact so many people fail the (very easy) drivers license written exam that it is common to hear histories about bribes to pass them. Americans complain about creationism taught in high schools, we complain about people not being able to do basic math.