Wouldn't that be great if violent cops were assigned to create Public Safety materials all day that went straight into the bin? They can't be fired so their job is to do something completely worthless until they quit.
Do you have to leave them in front of kids teaching students until they're convicted?
What if that takes months? Or never actually happens? But the teacher has crossed the line inappropriately enough times that no parent wants their kid in the same room with him?
In the most positive light, a union might protect a genuinely good teacher being unfairly accused or targeted for political reasons from being put out of work. But sometimes following the processes for ensuring that can be so unreasonable to work through on a practical level that it's easier to just keep them employed but away from students until it gets resolved or they quit.
There's a famous PDF that gets shared when this comes up (although it's geared toward an incompetent teacher):
https://reason.com/wp-content/uploads/assets/db/126393089187...
It’s also entirely possible that even without the unions, the school boards don’t want to get rid of bad teachers simply because they’re already, and chronically, understaffed.
Yes, it's not tech-level pay. But it's not exactly "abysmal" either.
Given the amount of education, time and their own resources they're expected to put in to do their jobs, I wouldn't categorize them as "good", and would say generalizing their compensation as poor would be accurate given those points.