There are very few institutions with enough students to guarantee publication of a course text. In the larger institutions, the professors' notes simply get published. There are very few stockholding bookshops for scholarly publishing, they only stock the required number of prescribed textbooks. Publishing in the tertiary sector is also difficult due to the transient nature of the education system. The apartheid heritage means that there is a lot of fragmentation, duplication and waste.
Many students never complete their studies.
Efforts are in train to rationalize. There is a shocking amount of photocopying but we are beginning to break through. New forms of electronic copyright are in the pipeline which will enable more user-friendly electronic publishing. Interim measures are needed. Most people who write books are scholars, it is surprising that they cannot agree on copyright issues.