It looks like you used 8 hours per working day in your calculations? Anecdotally, I haven't encountered a teacher who does a flat 40hrs a week. Also, summer break is only 2 months in LAUSD, not sure of the smaller districts.
As a parent of someone who went to an LAUSD school, my experience is completely different. Half the teachers didn't even bother to show up for parent/teacher night and were never available. The only teacher I'll give props to is the robotics club teacher, he was heavily involved, stayed late, but outside of him, that bell rang and it was a ghost town 20 minutes later.
