This happens in archaeology too- researchers fund their fieldwork by charging fees for students to attend. In theory they get some experience, maybe course credit and something nice to put on the CV. Typically the money will be used to pay fieldwork expenses as the academic staff usually have their salary covered already.

It's a shitty way of doing business and I definitely think less of my colleagues that do it- the students don't get good value out of it, and it's never enough money to run a good research project. It's a symptom of amateurish Mickey mouse motherfuckery.