Some try it and find out it's not for them, overall it is a pretty good idea.
From my Sister's experiences teaching, crazy superintendents, principals that think they run a harem or henhouse (depending on their gender), teacher cliques and liaisons, aggressively hovering interventionist parents, and school board members who are crooks or just too stupid and headstrong to understand how clueless they really are each contribute about as much to the problems in our schools as the unions do.