You're hired as a contract worker, essentially, and are only paid per class hour. So, if a student calls out sick, you do not get paid for that class. You could work like 13 hrs a/day and only get paid for 7. You accrue paid time towards grading and prep that doesn't come anywhere near the time you actually spend. All curricula is designed by you for each student individually. You have to communicate with each parent daily. Advancement is very difficult as there are few options if roles are taken. High turnover is inevitable. School charges 60K+/year to students, teachers should be full time employees with good pay. Less turnover, greater quality of instruction.
Students are often dealing with things that only a licensed therapist, psychiatrist, social worker, or other professional should deal with yet much of it falls on the untrained teacher. This is not fair to anyone involved.