It seems like it wouldn’t be difficult to identity those providing instruction as in many cases it’s probably the same people doing so. But how do they prove that compensation is exchanged? Do the customers admit to it not knowing it’s illegal? Or do they do so under threat of their pass being pulled? Or other means?
I think for the full exchange, they set up a sting and pose as a new student, but gather evidence as they go.
Once they have their own full transaction, they can link the sting txn to the past activity, even if that was more circumstantial. Then it shows a pattern and this was not not just a first offense, or entrapment.
To your point, I think if they have the customers, they could get them to inform on the instructor just with the threat of pass pulled and lifetime ban, but it might not always be needed.
They can just social engineer it and get the same info without needing threats (good cop).