At my kids' school, parents are notified, and the school Health Room Aide does a check of the kids. All kids. And also the other school staff volunteers to do head checks. And if a child has it, they cannot come back to school unless they were treated, and once back at school, the Health Room Aide does another head check before they go to class.
This is a public school.
Places like Whole Foods or other natural food stores, have lice repellants. That you can use to spray onto your child's hair and clothing.
At my kids' school as well, the kids are talked to, and told not to share hair things etc. It is precautionary. Kids are kids, and they often... play with each others hair or hug and sit closely to each other etc, and in Kindergarten the kids nap etc.
Precautions can be taken, by both the school and the parents. But these things only are helpful, if the school notifies the parents and the kids.
I know a kid that had lice in my daughter's class. And she has a younger sibling at the school too. So anyway, she had it, the sibling had it, the parents had it... and then other kids at the school. The parents, even if they were told, and the school sent home info about how to treat it at home... the parents didn't do anything right away to treat their kids. So anyway, that girl and her sibling had it like twice. And the parents too. Then FINALLY, the kid's parents, got more clued in, and treated their kids/the bedding etc. and then it finally was gotten rid of.
So there are these scenarios too.