> Nothing stopping them getting another job that works between the hours of 3-10pm during the school year

You don't think they just go home and do nothing at 3pm, do you? They still have to grade the work and plan the lessons.

My wife was a teacher. She generally worked from 7:30am till 8pm, sometimes as late as 10pm. I would usually drop her off, go to my engineering job, and then go back to her school where I would spend a few hours hanging out helping her or working or watching TV while she kept working.

And in the summer they spend a bunch of time prepping for the next year and learning new things at conferences.

Anyone who thinks that teachers only work 25 hours a week 9 months a year are sorely mistaken. She definitely did more hours than I did at my engineering job, despite the fact that I made more than 4X her salary.