If you're driving along a road and you know that there is a 80% chance that the speed cops will have a manned speed trap ahead and that the minimum fine is R 10000 would you be more likely to drive below or above the speed limit?
In SA the chance of a manned speed trap ahead would be more like 5%. Despite the high fine, people would still speed. If you want proof, just look at how many "law abiding" people drink and drive (this is despite the risk of prison time and a permanent criminal record!).