I'm married to a teacher, and more or less you are correct, though using the wide paint brush on this one isn't the right call.
The NEA is doing a hell of a job of turning the folks they "represent" into the most hated people going across the nation with their acceptance of crap performance.
Oddly, Colin Cowherd made a mention on his show, on how membership in a union gave one the option to strive for mediocrity and be successful financially in the long term, thats basically what the teachers' union does.
On the other hand, both of my sisters work at Charter Schools, non-union jobs, with higher salary and longer school hours (on top of what home time is needed), and are given performance based reviews. However, there is also a selection process to said schools, whereas my wife, in NEA land, has to deal with whatever **** comes through the door.
Just rambling at this point, but teachers are in a no win situation as far as public judgement goes, especially when they are forced into the union in order to work.
