it's like saying that if you arm people indiscriminately that you'll get someone irrational who uses the guns in the heat of the moment. teachers aren't police officers.
Police offices are just people just like teachers, just look up police brutality, police act in rage, and we don't deal with snotty little brats all day long.
What makes you think a police officer is Les likely to act in rage than a teacher, I actually know the opposite its true. I worked in the TYCJ (juvenile prison) and the amount of patience required there is far greater than the adult prisons. Juveniles have nothing to lose. So you have to be a level headed person to be a ps teacher, and maintain control far more than a police officer.
Your faith in law enforcement officers is astounding.