Why are teachers and other talkers paid less than engineers and other doers?

The meme below makes fun of unionized public school teachers, who feel entitled to the same salary and benefits as doctors, software engineers, etc. in the private sector. So, the point of this meme is simple, it’s to point out that the teachers who belong to teacher unions are ignorant of basic economics, specifically, the law of supply and demand. Basic Economics: In a free market, prices are set by supply and demand When there is more demand for a product or service than there is a supply for