Unlikely, south Africa is quite an outlier in Africa. Southern Africa is usually taken to include it an lots of other countries (eg. Tanzania). That as a group, is jot an outlier within Africa.
Tanzania is actually part of Eastern Africa and not Southern Africa. But you are right, Southern Africa constitutes a group of a countries while South Africa is a single country.
Ah ok. I agree. Generalizations about Africa are generally wrong. There's a world of difference between Cairo or Cape Town or somewhere deep in the jungles of the DRC.
There's really good map of planned and existing submarine cables to Africa at http://manypossibilities.net/african-undersea-cables/ which gives a fairly good idea of where the best and worst internet in Africa is