The most likely reason is that it is not comfortable for Western journalists to report from these places.

Just before Christmas 1980 I was in Kano, Nigeria when the Maitatsine riots broke out. For days the second largest city in Africa's most populous countries was convulsed. The official death toll was over 4,000 and this was likely low. There were arrows flying in the lorry park. The Nigerian Air Force was making supersonic runs on the old city where Maitatsine's followers were holed up. There were no stories in the international press.

At the time there were plenty of stories about apartheid. Could it have been that it was much more comfortable to stay in four star hotels in Johannesburg and drive out to Soweto where the security forces would keep them safe?