The entire U.S. agricultural industry is built on illegal immigrant labor.

No. It's definitely not. This is a kind of pervasive myth. To be clear, it wasn't built on it. Its not sustained on it. In fact, here in 2016, if its doing anything its just delaying the introduction of automatic picking robots that will replace workers. It might be the only upside is they can spend a little more time perfecting the new tech.

But having said that, there isn't much comparison to be made. English Training centers are so poorly run, mismanaged, so full of corruption, skimming, scamming, impeding foreign English teachers from success that the OP is right to describe 'the entire thing' as a scam, a fraud, a sham from the ground up.

This is unlike the British Banking systems, Russian oil or Diamond mines which are essentially solid producers of real products or services which have such high standards of ethics they will be constantly fined, reported, sued and even jailed when caught doing the exceptions to the rules.

Then its a kind of 'photo negative' comparison to be made. China's training centers (and really too many schools) are systems of shams, scam constructs which, occasionally have good people, are used for good purposes and sometimes produce some useful results. Which.. and this is the fun part... the good deeds are what will be punished. A manager who does not skim cash (or even worse gives helpful bonuses or cash advances) will almost certainly get scammed themselves before being fired for incompetence.