On the inside of teacher unions...tenure...
http://www.latimes.com/news/local/la-me-teachers3-2009may03,0,679507.story?page=1 Good teachers fired, horrible tenured ones kept. I've told my own tales and what I've seen and experienced back from my days of public education. Most either express their own similar disgust based on personal experience. Or nod their heads with an attitude of unbelieving, that it really couldn't have been that way.
But it is....
In high school, we had a teacher who only showed up on Fridays (payday). Yes, rumors abounded about her having a drug problem. We had another teacher fond of looking at the girls legs. Girls seldom ever got bad grades in his class, even if they only turned in half the work. And the joke running throughout the school was that his coffee had a healthy dose of liquor in it.
In elementary school I had a teacher make fun of my speech impediment in front of the entire classroom. You can imagine what that was like for a 12 yr old kid.
It's also why we intend to primarily home school our children. Because frankly, the few weeks I was home schooled I was able to accomplish more in 3 hours than public school did in 8 hours. Public schools are supposed to provide resources and guidance. Often they tend to provide distraction or conflict.