So we built giant organizations (political parties, nonprofits, schools, corporations) filled with easily replaced laborers. Unions fought back precisely because they saw coordinated action as the only way to avoid becoming commodities. Ironically, the work rules they erected merely exacerbated the problem, making every union worker just as good as every other.
Linchpin by Seth Godin- p. 10
This quote perfectly summarizes my feelings about the problem with teachers unions; they do not reward excellent teachers. Beyond the other obvious issues, (like asinine clauses in contracts such as prohibiting mandating that male teachers wear ties), teachers unions are impediments to their own goals because they make teachers easily replaceable as a business transaction, even when they are much more than that.