Obvious writing mistake: forgetting the world around you

This irked me to no end. There is a particular Japanese anime I'm watching. Now, I enjoy anime, whether its the kind for kids, teens, adults, etc., I enjoy it all, usually. I've watched both magical girl and hard sci-fi epics, enjoying things as they are presented.

And usually, there is much suspension of disbelief. That's a given for most anime. "It cannot happen in real life, but here is how it does in our fake world." - that kind of stuff is great.

But several series add in another factor: slice-of-life. Day-to-day things, or otherwise plotless events. Sometimes they serve for some character development, but usually they are just events taking place in real life, even if it's magical creatures doing them.

And oftentimes, only the main characters exist. You hear of parents but never see them. You know that people walk in the streets, but they either aren't there or are faceless. And all of that, I can accept.

This is what I cannot: In this anime, a girl suddenly appears in the male main character's life. Skipping along, she tries joining his school, but it turns out she is extremely intelligent and is recommended to a better school next door. She reluctantly agrees, with the (blockheaded) male encouraging her to go (thus separating them). At that new school, she says some things that others think are lies, even though they are true. The school administrators and principals don't believe her, and imprison her in a room until she "stops lying" - this is a girls private/boarding school. The main male finds out, and tries to save her. But the school guard keeps him out. He calls the friend of the principal, but the friend doesn't have the power either. So they resort to sneaking into the school to break the girl out.

Did you catch what's missing? CALL THE POLICE, DUH. It's illegal imprisonment. The guardian isn't the school. Even if they are allowed to keep the girl confined while on school grounds, they are not allowed to keep out the guardian of the girl! CALL THE POLICE.

There was no reason whatsoever for them to avoid doing that. Several other things I've read and watched at least explain why, in passing, but not this one.

I cannot believe something so obvious is left out without a second thought. Obviously, this adds drama and conflict to the plot, but it disgusts the reader/viewer.

If you write a book that takes place in a world with laws, and your characters DON'T call 9-1-1 or get authorities involved when a conflict happens, have a good reason why!