Author Stephen Pinker makes the most sense to me. He says that most people in the world are socially functioning as societies of law or as societies of honor. Where you have legal codes, people are systemically equal as the law tends to treat all individuals the same, and prosecution of the law is more or less even. Where you have honor codes, people literally take the law into their own hands. This has always been the case in all of humanity throughout history and the trend of course in modern countries is towards a society of law.
However there are parts of the world where democratic institutions are defective, or simply not trusted. So what do people do? They take the law into their own hands. Mafia. Drug Cartels. Gangs. Religions. Cults. Charismatics. Secret Societies. Alternative Lifestyles. All kinds of people in small groups for all kinds of reasons decide that The Law doesn't apply to them and they will deliver the kind of justice they feel is most appropriate.
You talk about my mama? I'm going to kick your ass! You rape my sister? I don't care what the law says, I'm exacting revenge. You blaspheme my god? I don't care what the law says, I'm going to cut off your head. You insult my people? I don't care what the law says, I'm going to do what I'm going to do. You disrespect El Jefe? You will pay in blood. Honor codes are not random, but they are inconsistent and irregularly applied as compared to systems of law.
Now obviously there are various mixes of these regimes. You can go into any neighborhood and ask the people what fraction of the democratic system of law they trust, and what do they think they need to take into their own hands. You'll get some combination. In the US, there are a significant fraction of people who have, for their own various reasons, decided against the legal system. For them, there is no justice in the justice system, so they opt out. They redefine justice as something to be delivered by 'the people' aka their honor codes. Unless and until they subject their codes to legal review and democratic vote, they can claim whatever moral high ground they wish, but honor codes can never and will never be democratic or embrace civil equality, and they will never be the law of the land.
Once you understand this phenomenon, all becomes clear. It is the central question facing American society today.