> For instance, at many public schools, teachers with master's degrees in education earn more than those without them.

Funny that the author should use an education degree as an example of a non-scam. Yes, it might have a positive return on income because of competition by credential-ism, but almost any teacher will privately confide that the majority of what they study for their degree is worthless drivel. A teacher could be trained much cheaper with a short course and then as an apprentice to an experienced teacher for a half a year.

[*] I'm not questioning the need for domain knowledge; a high school science teacher should have taken science courses. Irrationally, a high school science teacher typically has massively more "education" coursework than science.