The Land and Agricultural Development Bank of South Africa, as its name suggests, provides financing and technical assistance to the farming community. The Industrial Development Corporation provides loans to facilitate industrial development. The Development Bank of Southern Africa specialises in funding for infrastructure expenditure in Page 2 of 12  Southern Africa.
There are also a number of institutions that specialise in the financing and promotion of small businesses. Why does the SARB not engage in developmental activities beyond those traditionally in the ambit of central banking? The short answer is: because South Africa has institutions that are better equipped to do so than us.