Its South Africa dudes - you know white and black people aren't allowed to mix!
Seriously though, its more of a cultural thing. The knife community here is pretty much all male, white, older and largely from the Afrikaans speaking community, although there are exceptions to that in every centre, me being one of them. I tick the first two boxes but not the second two (although I'm getting closer to the third all the time).
The culture of knife use here is largely found in the rural areas, traditionally centered around hunting and fishing to some degree. Those areas have been dominated by Afrikaans speaking people for many years - the boers, in other words (
boer means farmer in Afrikaans).
So the makers tend to come from those communities and in turn sell to people from those communities.
Economics also comes into it. Although there are a lot of newly wealthy black people in SA, most of the wealth is still in white hands, to be sure. But I would say its mostly cultural. Black people here prefer spending their dough on cars, clothes, cellphones - things like that.
They like sharps, to be sure, but I think they would view spending a few hundred dollars on one a bit loony tunes. The average dude is happy with an Okapi in his pocket.