Libertarianism implies a private property regime with little or no public property or welfare state. We can't say categorically that an armed citizenry or contract security system would result in many more cases like Trayvon Martin or Ahmaud Arbery. Security firms wouldn't enjoy a monopoly of force or immunity from lawsuit. We can't know if these men would have had access to the places where they met their ends.

Taking examples from our corporate statist world and saying these things would happen under anarcho-capitalism is speculation at best. Libertarianism does not promise utopia but an absence of coercive transactions at the hands of the state. It does not preclude voluntary collectivism either.