I think that many just don't know how widespread, deeply ingrained and recent much of this was - they think there was slavery, a bit of racism hanging around and then (in the USA at least) the civil rights act sorted things out and made everything equal. And that's really similar in nature to the comment you replied to - people have picked up a simplified and wrong version of history of Warsaw Pact countries and they're just a bit ignorant of the truth.
In the USSR, peasants were essentially serfs. They only got internal passports in the 1960s and 1970s, and without those they could not leave the village without permission. They worked for a state collective farm, most of their pay came in just counting the "labour-days" they contributed - a totally self-containbed, essentially prison-like economic system.
So yes, I agree, I originally brought up serfs as being something from 150 years ago, but it was more like 50-60 years ago.
It's not quite life-on-the-reservation out there, but it's not far from it.
They were never any good, and as soon as the planned economy stopped pouring money and work/busy-work into those areas, they all went straight to shit.
50 years ago a lot of their descendants in the Eastern Bloc countries were probably still in that condition or in the USSR factory worker equivalent.