Old European saying, "If they are roses, they will bloom." The idea is that if you have talent, it will show itself. I go further: If you are smart, you won't be kept ignorant for long.
So why are teachers the "whipping boy" for all politicians? Blame the students for not trying. If you don't have talent you won't make it. So try harder. Stop blaming someone else.
By the way, what's the point of all this dumb evaluation? The late Steve Jobs didn't get "evaluated" by someone (except the marketplace). If it was left to his employees, they might have given him a bad evaluation because he tended to yell and pressure folks (that's maybe why he was a success). He was his own boss and did what he wanted. Same with all the other billionaires. They weren't evaluated.
Be your own boss. Get out of teaching; you can't ever please these folks. Everyone --parents, principals, students -- is your boss as a teacher. Everyone, including the President of the U.S., feels they know how to do your job and has the right to criticize you. I admire the Teamsters. Nobody pushes the Teamsters around. Nobody "evaluates" them. They just are left to do their jobs. Don't trust the "Dilbert-like" boss to evaluate you.
To those who stick with teaching, I admire you. All teachers are good teachers. They're the ones doing the real work. Not their critics.