Elementary school kids are huge on fairness and injustice. It seems like it's built in to facilitate group social dynamics in great apes. It takes a lot of sophistication to be able to frame valuing fairness as a character flaw.
https://pmc.ncbi.nlm.nih.gov/articles/PMC3283570/
Downvote if you like, but kids' community values are typically enforced with antisocial behavior
