I really hate how I find myself having to go to greater and greater lengths to disclaim my words around here to not have them twisted or stretched to imply something.
US murder and incarceration rates are more or less solely caused by the war on drugs. Once you remove people who are involved in the manufacture, transportation and sale of illicit substances from the crime stats the place looks a lot like the better parts of western Europe.
Yes, wealth equality, social mobility and healthcare have a hell of a lot of room for improvement but they are not the driver of violence in the US. Forcing a multi-billion dollar industry to exist outside the law is what is driving violence.
> US murder and incarceration rates are more or less solely caused by the war on drugs
That's what you would expect if drug trade is the most profitable crime, no matter if drugs are the reason these people went into crime in the first place. If you can't afford your expected lifestyle within the system you go outside the system. Once there you choose the crime with the highest profit per risk factor.
There's plenty of countries that penalize drug ownership that have order of magnitude less crime than USA.
The crazy high crime, murder and incarceration rates in USA aren't caused by population size. They are caused by inequalities inherent in American system.
If a whole class of your society can't hope for their kids to get a white collar job, and have to fear losing their house if they ever get seriously ill - that's not a stable basis for a peaceful society.