For no reason whatsoever besides credentialism.
very long hours with no flexibility
My dad worked hard as a teacher. But he didn't work 60 hours a week or anything like that. He'd grade papers while the kids were doing homework.
low pay even before you adjust for true hours worked
Two months vacation.
and you are given very little professional discretion.
I agree with you here. The constraints put on teachers and schools by all sorts of outsiders are very limiting.
Most of them are because the people paying the bill want some sort of feedback and control mechanism. Instead, I think teachers should be given great leeway, but also be very easy to hire and fire. If a parent isn't happy with their teacher/school, they shouldn't need to appeal to the schoolboard to place rules on the teachers. Instead they should be able to vote with their feet. Exit beats voice.
To put some facts into the discussion: this assessment by the American Statistical Association found that teachers are responsible for 1 to 14% of student's test score variance
If the theory is that teachers aren't that important, we shouldn't worry so much about who they are, or if we are paying enough to attract quality teachers. NB I am not saying I agree with the antecedent.