Just park your car and look out your window when the kids come out of school. If you don’t like how they act, then don’t consider the school for your children. At least that’s what my relatives do. Since many of them live in Washington, DC, they send their kids to private schools.
Good choice for them and they sound like real good parents, not willing to sacrifice their children’s future for over-wrought notions of cultural diversity, especially ones that are self-destructive.