Oddbean new post about login | logout it's a distraction
no, Teachers unions are notorious for keeping bad teachers. Regular work unions have to keep bad employees. The fight for higher pay and benefits is costly to companies
you're generalising from the exception not the rule. also, there's lots of evidence that shows there's actually a high cost to not providing decent pay and benefits to workers.
This is very common though. Unions are good in theory but fell to corruption and abuse like everything else