It sure as hell is the schools job to protect children while they are on school grounds. And you calling an 11 year old girl, a snowflake because she was upset at being tormented by bullies is despicable.
Bullies are more often hard to detect because they are also cowards and will act behind the teachers back. They do not want to get caught. The parents and the little bastards are the ones to blame. A teacher may have 30 kids in a class, can’t watch all of them at the same time. Also when a bully does get caught, they will be meaner next time. Best thing is to teach kids self defense. I personally knocked teeth out of a bully. He never bothered me again, and I got respect from the other kids.