Jerry Pournell, one of my favorite science fiction writers, has developed his Iron Law of Bureaucracy which I believe is a very accurate description of government schools. Below is one of his earlier versions of the law.
Pournelle's Iron Law of Bureaucracy states that...
In any bureaucratic organization there will be two kinds of people: those who work to further the actual goals of the organization, and those who work for the organization itself. Examples in education would be teachers who work and sacrifice to teach children, vs. union representatives who work to protect any teacher including the most incompetent. The Iron Law states that in all cases, the second type of person will always gain control of the organization, and will always write the rules under which the organization functions.
In later versions he substitutes "school administrators" as the second type of person. Pournell's law is very similar to the Iron Law of Oligarchy a political theory, first developed by the German syndicalist sociologist Robert Michels in his 1911 book, Political Parties.