I had to look up MVSN. They were the Italian Fascist Blackshirt thugs.

If you think life in LA would be improved by the absence of the LAPD, I strongly question your grasp on reality. If you think the LAPD hassles people they shouldn't, beats them up, and sometimes kills them, you're almost certainly correct. But if you think that, in the absence of the LAPD, the total number of beatings and killings would go down, you're dreaming.

But you said, "Why would I approve of, say, the LAPD any more than I would approve of the MVSN?" My reply is that you would approve of the LAPD and not the MVSN, because despite the brokenness, the LAPD is still a net positive, and the MVSN were not.

It may well be that some paramilitaries are more efficient than others, but their incentives are by definition always stacked against community building, and in favor of adversarial enforcement.