Most commenters in this discussion badmouth the traffic cops, and speeding laws, because they assume that these laws suck in South Africa, just like they suck in their own country like the USA or the UK and so on.
But in fact, when I visited South Africa, I was suprised to see that the situation is actually different - and better - in South Africa; In much of the rest of the world, speed limits are relatively arbitrary. E.g., the speed limit used to be 50 miles per hour throughout the US (although this changed somewhat in recent years), and is 90 km per hour in highways throughout Israel. Since modern cars can easily go much more than that, drivers have gotten used to break the speed laws all the time, and (rightly) feel the cops are pigs (to use the original poster's terms) and are out to get them - not to catch criminals.
But in South Africa, my experience (from driving along and around the N2 for about a week) is that the speed limit on the highway is *not* arbitrary. Every few miles, the speed limit changes depending on actual road conditions - sometimes when the road is bad, it is just 90 km/h, but in good stretches, it becomes 120km/h. My feeling in South Africa was that indeed, someone who goes over the posted speed limit is really doing something wrong. It is really dangerous to go over 120, and when the speed limit says 90, you would really be stupid to do over 90 because there is a real reason why this limit, and not 120, was posted.
When the speed limits make sense, and only criminals and crazy drivers break them, why would you want to fight a system to catch those criminals and crazy drivers?
So all the people badmouthing South Africa on this thread - better learn from South Africa (at least on this issue...) instead of just assuming that everything is wrong in that country.