I adressed this issue on another Medium article about this subject. People are conflating Nelson Mandela with ANC activist Stephen Biko who was in fact murdered by SA security forces in 1977. Peter Gabriel made a music video to accompany his song 'Biko' in 1980 that includes scenes froms Biko's huge funeral. That's what people are thinking of. I bet that NO ONE that is actually in South Africa is making this mistake.