Earlier quoted context omitted.
US teacher salaries are abysmal. When education funding gets cut the school boards the unions successfully negotiate stronger employment protections (after all, if a job pays poorly you need to attract employees some other way, such as good PTO, benefits, or in this case: a job for life). It’s also entirely possible that even without the unions, the school boards don’t want to get rid of bad teachers simply because t…
US teacher salaries aren't nearly so bad as you're thinking. Median is around $60k, which compares favorably to the median household income of $59k - and teachers get better benefits, too. 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.