It is a travesty that the only way to advance your career as a teacher is to leave the classroom. No raises, no more responsibilities, no more prestige, unless you stop doing the thing that, if you're any good at it, needs doing the most. And so talented, hardworking people stay underpaid, and those who don't care so much about student interaction move on up, making double or triple what a classroom teacher does.
And even those who do care, who love the classroom and students and who get it - within 2 or 3 years away from daily teaching, they've forgotten. They've been seduced by fancy looking paperwork and rubrics that no one will ever see; by color copiers and real duty-free lunches, by politicians who don't understand education telling them what good work they're doing...so they take the money and create the forms and hold "Professional Development Opportunities" that just showcase how far gone they are from real teaching.
And those who could make change, who really see what the problems are and where change needs to happen, are too busy grading papers and emailing parents and opening milk cartons and adapting homework assignments for 10 different students who need individualized lesson plans in order to reach their potential to do anything about it, except for recognizing that if they leave the classroom for long, their soul will lose its spark and they'll no longer be a part of the solution, but rather a part of the problem.