It is good that young Erin learns early that government, at every level, is capricious, vindictive, and stupid.
That's absolutely the lesson she should learn!
The only one stupid is her parent who is “proud” of her for helping enable and cover up her friend’s illegal behavior instead of reporting it to the child’s parents. The school’s policy is probably that she should not be in attendance at these illegal parties. She was and she didn’t need to be.
No one’s saying her violation was severe, but her punishment of missing a few sporting events is hardly severe either. She isn’t missing any classes or schoolwork or being asked to put in extra time in detention. It’s appropriate.