In my country (Chili, that's the "that's why" of my avatar) there's a huge jump between public and private schools. Private schools are far above public schools' levels.
We get 14 years of school in which you can't fail two classes or you simply don't pass the year.
In my school particularly, if you failed 2 years in a row you were out. But my school was particularly tough (no wonder we were studying form 8AM to 6PM almost every day in the 4 last years).
When you finish school there are big university entry exams and depending on your score you can apply to a good career and/or university.
The good thing is that even if private (i.e. expensive) schools are better, public universities are still far better than private ones.
It's interesting how different can different countries' educational system be.