It's not crazy man. Some students really don't give a fuck. I'm not saying the girl in the OP was the case, but some students don't care and sometimes their selfish mentality will allow them to be disruptive without regards to other students.
There are alternatives, but those alternatives have been struck down by these new aged parents. The liberalism of our society has made discipline within a school environment a little more difficult. The sad result was the policing of schools. They actually have authority to handle child a certain way versus the teacher. Teachers get fired and sued on petty shit.
Parents to the teacher: "don't put your hand on my child."
Parents to the police officer: "don't put your hand on my child."
Teacher to parent: "come for a conference so we can discuss your child's schooling and behavior."
Parent: *no show*