The unions aren't blameless, but I don't believe they are solely to blame. The politicians and judges deserve a share as well, as do administrators, teachers, parents, and students. I don't think any one factor is solely to blame.
Every school has several teachers who don't know what they are doing and turn kids off. Right?
I already said there are bad teachers out there. Some schools have more than others. Of course, every school I've ever been associated with also has several fantastic teachers on the other end of the spectrum, and quite a few who are average.