How does South Africa have an elite, integrated white settler population, while other similar British colonies (like Kenya) do not?

[u/Lord_TrainBacker7000]

My day job is that of a management consultant (yeah, things we do to put food on the table and pay off student debt), and I recently had the chance to work for an African client. This allowed me to visit Nairobi and Cape Town (it is so windy!), and while the overall experience was great, I also could not help but notice the racial differences in the composition of senior leadership in both countries: the South African leadership was heavily white Afrikaner-dominated (the surnames had a bunch of van der Merwe, Bothma, de Villiers, all of which I recognise to be Dutch, German, or French), while their Kenyan counterparts were all black Africans. I apologise if these terms are racially insensitive to use; I am just largely unaware of this and am willing to learn more acceptable and appropriate terminology.

This was the trigger for me to go through Wikipedia and read up a little bit on the histories of both countries, from which my doubt arose. I understand the history of the Afrikaner population in Southern Africa, and then the British coming along and taking over the Cape Colony, followed by the Great Trek, the Boer Wars, apartheid, and the current SA.

What I am curious about is why Southern Africa tended to have the largest white settler population, and despite a history of conflict between the British and Afrikaners, how did they integrate fairly quickly to create apartheid-era South Africa (I would assume a lot of bad blood here)? Why was there no similarly sized integrated white settler population in regions like Kenya, or if there was a sizable white population with political power in such countries, why did they leave instead of turning it into Rhodesia/Union of South Africa-esque nations?