The content of your post is more prevalent, no doubt some quit for the OP reason too.
When I finished Geology, I went into accountancy, then retail, then finally construction. In the mid 90's, my mother said I should go into teaching but I said, "If I did, I would be sacked for clouting a student". Even back then, behaviour was declining. In 2004, I had to do 3 years construction courses at college. I tell you what, thank goodness I never went into teaching, the students wanted flogged.
Schools should have cameras in classrooms and parents fined for their kid's poor behaviour.