It is clear that there are situations in which the unions’ interests diverge from the public’s interest in transparency and good policing. But the unions’ interests also often diverge from the interests of individual members.
A "good" education consists of learning how to spot "trick questions" that lead us astray from clear thinking. We often see that every "free lunch" offered by politicians involves at least one trick question.
If US states are able to act independently, there is a greater chance for competition between jurisdictions, incentivizing states to provide a higher quality of life and to attract productive newcomers.