Value is subjective, but IMO educating the next generation is very valuable. I think their pay is low because taxpayers are stingy. The low pay is only an indicator of what taxpayers think, which only shows that they are low value if you think an appeal to the masses is a valid argument.
That's a retarded statement. If education was so valuable then parents would bid up salaries for private school teachers and force up pay in the public sector. If anything, taxpayers are overpaying. Taxpayer preference provides a floor, not a ceiling.