School shooters are almost never outsiders. They're current or recent students of the exact school they attack.
They know the layout. They have grudges against specific peers or teachers. They leave the evidence of their social failure, isolation, and resentment right there in the building.
So the one institution they all share, the modern public school, is treated as the neutral backdrop instead of a possible contributing environment.
What if the system that warehouses adolescents for six or seven hours a day, sorts them by age and status, weakens family authority, and replaces older moral frameworks with therapeutic and identity-based ones is doing more than just "failing to prevent" these events?
Most kids don't shoot up schools. But the ones who do are almost always products of that same institutional environment. That pattern is hard to ignore once you stop treating the school as irrelevant to the outcome.