It's so obvious, and an absolutely accurate way to judge the quality of a jurisdiction. People in prison are the weakest people in society, weaker than children (who usually have the ability to walk away from home whenever they want, although they're subject to being searched for and returned.) As the weakest, nominally least deserving people, benefits given to the prison population filter through the culture. You can't give good health care to prisoners while people who haven't committed crimes (including the victims of those prisoners) go without. You can't give adequate housing to prisoners without giving it to everyone. You can't give free education to prisoners without giving it to everyone. You can't give prisoners freedom of speech without giving it to everyone. You can't give prisoners the vote (and convenient physical access to it) without giving it to everyone.

Start with prisoners, and you elevate everything. Instead, in the US we racistly fantasize about interracial sexual assaults, make people shit in front of each other, and make them work for 15 cents an hour. It's obvious what society has to look like outside of the walls.

And were not talking about prison here; this is jail. Everybody there is innocent. The state should keep them comfortable, and spend as much effort trying to come up with reasons why they are not guilty as reasons they are guilty. Instead, it's just pre-prison.

You don't even have to go into a prison to hear people in the US gleefully celebrating the misery that takes place there.

Prison rape is treated as something to laugh about, not as unconscionable violence.

There are 2.3 million people incarcerated in America. 5000, or 0.2% of them, died in jail. A 99.8% chance of not dying in jail for those 2.3 million people is thus indicative of a society with high degree of civilization. Fyodor would call our jails health spas compared to what existed in Russia during his lifetime between 1821 and 1881.