The 10-month working year is a core issue here. It's hard to convince voters and other government workers that teachers deserve a X% or XX% raise, when teachers receive 2.5-3x (summer break, plus other holidays) more paid leave than the average American. That paid leave is worth something: I think many people would choose a job with a $50k salary and 10 weeks of leave over a $60k salary and 3 weeks of leave.
The obvious fix would be to get rid of the summer break, and give teachers a ~20% increase in salary to compensate them for the increase in working days. This would solve other problems as well: Summer break causes serious childcare problems for working-class families, and research indicates that it probably hurts educational outcomes as well. However, this is unlikely to happen for various reasons: It would stretch (or over-stretch) the limited budgets of local school districts, and summer break is politically popular and has relatively powerful state-level lobbying from tourism-related businesses.
The obvious fix would be to get rid of the summer break, and give teachers a ~20% increase in salary to compensate them for the increase in working days. This would solve other problems as well: Summer break causes serious childcare problems for working-class families, and research indicates that it probably hurts educational outcomes as well. However, this is unlikely to happen for various reasons: It would stretch (or over-stretch) the limited budgets of local school districts, and summer break is politically popular and has relatively powerful state-level lobbying from tourism-related businesses.