PBS? Gosh, they're totally objective.
There are 1000 fold examples of exactly the opposite of what you state. The unions exist for the benefit of the union. Not the teacher members, not the students. When payment of union dues was no longer accomplished by compulsory payroll deduction in Wisconsin, dues collections plummeted, No perceived value I'd guess. The long running tragedy of the union scam is finally being exposed and only in the fairy tale world of government employment is membership rising. Of course, that's no surprise since the federal government has done such a swell job of managing social security and its other "math doesn't matter" Ponzi schemes.
Good luck with your union kool aid chugging there "everyone..."