|Image Credit: Indian Folk|
It doesn't really matter what they're teaching or how well because they already getting paid upfront. If students end up quitting or not receiving the right information that's applicable or useful to them, then they're SOL. The teachers always walk away with a paycheck every time.
Teachers don't really have to work hard because the students are doing the leg work. The responsibility falls on the students to understand and learn whatever the teachers giving them. The end result is what the students learn as much as they can or how well the know/do and not how much the teachers teach or their teaching effectiveness. Their payment is tied to the service of giving out information, that's it. Not how well the students learn or know. They still get paid the same if students don't learn or do as well so there's no incentive to make sure failing students do better.
It's a lot easier online because, there's less quality control in education sites (ie. Udemy and Skillshare) and people don't need qualifications to teach that makes sure people are being taught effectively.