[kageneko]

My wife was a teacher for ~10 years. She made a nice salary, but she also spent a pretty good amount on supplies for her classroom since her school was routinely overenrolled and underfunded. She also had to spend money on classes and certifications every few years in order to maintain her license.

Georgia (at the time) gave bonuses and increased salary for additional degrees and specializations, so there was some incentive to improve. When she left (mostly because she was tired of dealing with parents...) there was talk about removing the higher education/specialization bonuses, but I don't know if that came about. There's also no union. There are a few professional organizations, but they don't have bargaining power.

I think in the United States, it's really hard to talk about teacher experience as a whole, given the different laws and situations.

[neap24]

True, but given the technical age we live in, I think supply costs are rapidly diminishing. I also happen to think that "school supplies" are vastly overrated (having taught in Teach For America in an underserved school myself). Furthermore, why do you think that an incentive for advanced degrees/specialization is a good incentive? I think that's the worst kind. The teachers I've met with advanced degrees do not even seem to correlate with the best teachers.

I'm not saying your point isn't defensible, it's just that saying teachers/districts are underpaid is far from the obvious answer.