It’s the Weberian definition of a state [1]. When non-state actors freely use violence to further their aims, we call it a failed state.

[1] https://en.m.wikipedia.org/wiki/Monopoly_on_violence

no single crime, violent or not, really challenges the state's monopoly on violence

> no single crime, violent or not, really challenges the state's monopoly on violence

Sure. And many murders remain unsolved. We treat murder differently from other crimes that result in human death in part due to instinct, but in part because when we don’t it becomes a political tool.

I wonder if there's a name for this rhetorical device: like casually insert shocking statements about atrocities committed by those in power. Chomsky uses it extensively.