Currency
Even though many of the main cities in South Africa (Durban, Johannesburg) cater to the international business world, the reality is that South Africans are fairly disconnected from the notion of the dollar. The currency in South Africa is the Rand and data shows that the South African gambler would much rather gamble online in Rands.
If you are planning to engage in business with South Africans, it would be a high plus if you could find online gambling operators with availability for transactions in the local currency. However, some of the biggest brands that are already doing business there have been doing well with the dollar, the euro and the pound. Whereas this isn’t a determining factor, your website might get a few extra looks if the Rand has an important role in it.