A couple of years ago, I spent some time in South Africa. At one point I asked a local friend what they thought about the song "Sun City"[0], which was an anti-Apartheid song from 1985. My friend never heard of the song and was shocked since so many big artists performed on the track. They proceeded to ask their friends on Facebook, many of which were in theirs 30s/40s, if they heard the song, and the far majority of them also never heard of the song. The government was very effective in blocking access to the song via all the normal channels for the time.

[0] https://www.youtube.com/watch?v=X36NC-mIbq0