I dont see why ISP's dont build their own local loop...
Probably waiting for the cheap and easy option. Until then, we should be bashing them and not telkom as they are the ones who refuse to spend their own money on their own network.
Cost. Buying up right-of-ways, dealing with copper thieves, laying copper to every house you service, training and hiring technicians, etc. In the end it will cost more than Telkom can offer it for.
http://en.wikipedia.org/wiki/Natural_monopoly