They need a host culture
Or a subject race, perhaps the remnant of r*SSians after the war.
There are certainly some cultural taboos, however since r*SSians have very few, of any, standards, they would be good as serfs to the Roma people.
Amish
I saw a film of the appallingly primitive way some r*SSians live, in villages far from Moscow. There were parallels with the Amish however unlike the Amish, they didn't have any culture or religion. Worse clothes too, The Amish always seem to dress well; the r*SSian villagers were just wearing very diverts nylon tat.
many other countries like the US (and UK) are trying to mimic that stratification
I just read "Welcome to Everytown: A Journey into the English Mind" by Julian Baggini. A book written in about 2009 based in a year he spent in a postal code district that is according to census stats as typical as it gets in terms of old/young, white/BAME, religious/non-religious, more/less educated, owner occupier/renter etc, etc. The area is not unfamiliar to me since I lived there once, a long time ago, The book was partly to shock people who live in hipstery places or more cultured urban areas, to stress that on the whole, the white working class are still the majority and a few other things. I'd just been reading about standards of life in r*SSia and the contrast hit me between the awful, grindingly poor and hopeless life in r*SSia, the endemic alcoholism, the violence and the hugely stratified society there and the more genial, community minded and kinder life in the poorer parts of the U.K.. That and the material differences between the poorer parts of the U.K., its social housing (we did Socialism properly) and the squalor of r*SSia. And of course 100% of homes there have indoor plumbing.
There's also a chance of social mobility, a chance to get out and do something better. In r*SSia this is only possible through vi9lence, crime or prostitution.