The problem is that teacher compensation has not scaled with educational spending over the past few decades in the US. K12 spending in the public sector has increased faster than inflation * population growth everywhere, yet median teacher pay has gone down (I think average is stable but that's because some senior teachers get really sweet packages).

Even if states cut education budgets sharply in 2008 it shouldn't have been a problem, because it's not like teachers 30 years before that were suffering under much more parsimonious spending. It's just that when they cut those budgets, someone decided to pass the pain on to the teachers instead of figuring out where the real waste was.

The atrocious thing is that the teacher's unions keep clamoring for more educational spending instead of higher teacher pay. Empirically speaking in the US, more educational spending will correlate with lower teacher pay.