Not true, and--even better!--I have proof that your statement is false:

First, black Nelson Mandela became President of South Africa in 1994, almost a quarter-century ago. Second, the white National Party was completely dissolved in 2015, which was 12 years ago.

So, I present you with proof positive that white South Africans have indeed shared power.

This is all historical record. How is it that you've missed all that?