I actually taught at both the High School and College levels for a number of years. History, and Life Sciences in Secondary Schools; Western Civilization, and Logic at college level.
You are correct in that much is expected of a teacher both in and outside of classes. Lesson plans, student projects, lectures, science experiments, grading student classwork and tests, negotiations with administrators, parent/teacher conferences (or confrontations in some cases), extra-curricular activities to name a few job requirements. All the while dealing with students (and their parents) from all social strata, ethnic backgrounds, nationalities, language groups, and the varying/conflicting attitudes they display towards the value of education.
It can be a tough job, if you are trying to do it right. The pay isn't really that "demeaning," but it doesn't cover all the pre- and post-classroom work required to do the job properly. You also have to be very self-motivated because it isn't as heart-warming and up-lifting as they used to portray in those old movies.
I think this is why the Left is so successful at it. They don't seem to really work at actually teaching subject matter, instead using their position and classrooms as platforms to indoctrinate.
That's my opinion anyway. :shrug: