No paid holiday leave.
No paid sick leave.
No paid maternity leave
No employer pension contributions or health insurance
It takes a very long time to get enough students to earn the equivalent of what you would have earned from day 1 of a normal job.
There is no progression, no career ladder, nowhere to go.
If the kids are sick, busy or on holiday you don't get paid.
Almost all your work is outside school/office hours, which is no good if you have a family.