That sounds so frustrating for your granddaughter, and I hope she finds something that feels good for her, we all deserve that.
One thing I've learned is that US culture is punitive and violent. When I stopped punishing and started discussing (yes, it takes time, punishment doesn't), everything in my house changed and now I have good, happy, empathetic children.
I was very petite in my gang days but I was also the person you'd not want to cross in a dark alley because I would win whatever altercation went down. Now that I'm fat, probably not as much although I haven't tried because I'm committed to nonviolence.
I also oppose the removing of phones in classrooms. My oldest was the victim of severe bullying and the school always said the cameras were broken so they couldn't see what happened. I told her to record the incidents herself because they said we needed proof but then they told her she wasn't allowed to record. But having the phone made her feel safer.
I have found that if children are disrespectful to adults, the adult has usually not had respect for the child.
It's complex and the kids with disorders (which is very real), and kids with bad lives at home will often act out and instead of defaulting to punishment which rarely works, we need to be finding out the root.
It's complicated and I've known several excellent teachers, many average teachers (which is just fine), and several people who had no business teaching. I don't think school is easy for the students either.