The original quoted statement in GP is a pretty common thing I have seen in younger people in now-prosperous former-communist central/eastern European countries. Minorities being subject to institutional racism in the form of apartheid, redlining and such is completely handwaved away and countered with "we had it bad under communism, but we recovered so why can't they". There are thankfully a growing number who don't think like this, but many simply cannot be convinced and will dismiss your explanations as excuse-making, or try-hard "woke"-ness. Hell, I've even encountered guys here insisting that because they're so non-racist they can use the n-word.

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.