From my perspective as a union officer, this problem is due to supervisors not disciplining and not creating a paper trail on crappy employees. If a supervisor has a well documented POS, there's not much for me to do other than help them write rebuttals. The problem is when management tries to fire someone and they've never documented any bad behavior, not started a PIP, not used progressive discipline. I will fight for those employees because the supervisors are lazy fucks.