As a senior studying high school education, I can't agree with this thread more. There are way too many lackadaisical teachers who can give a rat's ass about their students and how they actually teach. There are two reasons why in my experience:
1 - Teaching isn't viewed as a profession. If it were, teachers with professional degrees (I.e., masters or equivalent) would get paid like a professional. Professional lawyers, doctors, accountants, actuaries, contractors, and businessmen all get paid way more than teachers. Most teachers in this country with a MEd make about $50k a year. That's disgusting.
2 - The teachers unions are destroying schools. The crappy teacher who doesn't care about anything but showing up and getting checks every month simply cannot be dealt with. The unions have a vice grip around the testicles of the school boards. Instead of firing shitty teachers, principals simply write poor reviews, year after year. But the principals know that it's useless, as do the teachers.