Indeed. I grew up in a cultural milieu that was overwhelmingly Slavic (Chicago suburbs, mostly Czech and Polish but smaller numbers of Slovaks, Slovenes, Croats and Serbs) and even within that, the lack of understanding of distinctions was surprising (so many people thought Slovak and Slovene were the same thing, which isn’t helped by the fact that the countries have very similar flags since independence and near-identical demonyms in their own languages) although I would note that the Slovenes, Croats and Serbs were all highly aware of the distinctions between themselves and even as cultural self-identification as specific Slavs in Chicago has faded, there’s still a low-level hostility between Slovenes/Croats and Serbs.