Other African nations that didn't have Apartheid or similar institutions have similar economic and political results. And even the one sub Saharan nation that didn't experience colonization, Ethiopia, isn't screaming ahead of its neighbors economically or otherwise. Its GDP per capita is slightly ahead of Uganda's and fairly far below Kenya's.
Also what point are you trying to make here? You seem to be implying a common cause for these results. Care to explicitly state it?
Countries that have developed in the last 60 years tend to have strong authoritarian leaders and the favor and interest of Europe and the United States.
Ethopia does have natural resources but it doesn't have a strong central government, partly because the warring factions want control of the resources. Places like UAE, Saudi Arabia, and Qatar had strong dictators before they developed the petroleum industry. African states that have oil tend to be too weak politically to resist outside interests taking the wealth by paying bribes and funding warring factions.