How do you determine if someone is underpaid or overpaid? Is it just who shouts the loudest?
Is there some standard by which we might answer this question? Well, in fact, there is.
If teachers make $ 50,000 per year, for example, some might say that that isn't enough. After all, they are teaching our children. What is enough? Is there ever enough? Especially, since they are "teaching our children," no matter what the salary. This is an argument with no salary limit. But, what is the real answer to this question.
The answer is simple enough. Are there other folks equally qualified to be teachers who are willing to work for $ 50,000 or even less? What is the answer to that?
There is not a single school district in the United States for which there is not a long line of qualified applicants, who would love to teach in that district, but cannot because there are no openings. What does that mean? It means that teachers are much more likely to be overpaid rather than underpaid. Why? Because lots of folks like to teach, especially young college graduates, and are willing to work for less money to pursue a vocation that they enjoy. So, there is no reason to raise teacher salaries and there exist fairly strong empirical grounds for lowering teacher salaries (and benefits) until supply and demand are brought more into balance.
The situation is even worse at the college and university level. Tenure means that faculties age and atrophy while talented younger academics cannot find positions. These younger Ph.d.s are typically better teachers, more engaged in research and willing to work for far fewer dollars than their ossified tenured brethren. But, they cannot get in the door. College and university teachers are overpaid. That's one of the (many) reasons that college costs are out of control.
When you overpay a group of employees systematically, then you end up overcharging the consumer of those services -- our children and the taxpayers. You can't cut a special deal (tenure, whatever) without damaging the interests of those who have to foot the bill. For the sake of taxpayers, for the sake of our children and the families that provide for our children, we need to get realistic about what we pay teachers at all levels.
It is no accident that private school teachers are paid substantially less than public school teachers. Why? Because the private schools pay market rates. Public school teachers are overpaid.