For example, let's assume for the sake of example that objective evaluation of teachers and even schools is impossible. This is true in other jobs in the service industry.
Then it should be possible to have a subjective rating system that is accessible by consumers (parents, students) and employers (schools). Teachers that relatively rate well would benefit. Teachers that rate relatively poorly would have incentive to improve. Teachers that cannot improve could either be supported by their bosses for their good "intangibles" or be removed from their positions with better evidence than "Well, I think he is a bad teacher".
Thought experiment. Why doesn't this happen?
* Parents don't always have the ability to switch teachers or schools, so there's a lot of conflict of interest in providing publicly available feedback; students shouldn't suffer more because their teacher is called out for something.
* Unions absolutely don't want this. They get more power in numbers, so there's very little incentive to serve the top 10th percentile and introduce risk to the bottom 50th percentile.
* I don't see why the education regulators would care about this approach. Ask a regulator for solutions, and you'll get regulations (standardized testing, lunch nutrition standards, etc.).
* Teacher pay would have to be more subjective and negotiable (set by the superintendent or something). This means all the teacher contracts would have to be renegotiated.
* Teacher mobility is low. Jumping to a new district in a different state that takes good ratings seriously might actually involve a loss of seniority and a pay cut.
* New public schools aren't going to be started to "try this out". Private schools, maybe.
* So, ultimately, school districts don't tangibly benefit from a change like this. They benefit more from property values going up. Or from more student attendance.
* Finally, given all of the above, who will build Yelp/LinkedIn for teachers? It seems like a political hot potato with plenty of external barriers to actually working. Maybe legislators or regulators decide to design one by committee, but I'll be skeptical that they can create a product that gets any real traction that way.
I don't think it's a particularly great idea, to be clear. I'm just exploring why established parties aren't interested in change. And I don't say that to say everyone in education is uniquely greedy or self-interested. I think people in education often have noble hearts, but they're people at the end of the day, like the rest of us. Putting nobility at odds with economic interest limits achievement. We're all human, after all.