Aren't they required to have previous schooling in their home country, pass an aptitude test against others, and maintain good grades to stay in the program in

Aren't they required to have previous schooling in their home country, pass an aptitude test against others, and maintain good grades to stay in the program in order to stay in the country? I don't see how you can avoid actually doing the education part here. And I'm sure lots see immigration + better education as a win/win, which I don't see a problem with. Where are you getting the huge percentage from? Do you have sources for your claim? Even news articles?