The thing with speeding cameras is that they could easily be adjusted to allow for 20% (say at most 20kph) margin (which would be perfectly fine for me even on the German Autobahn), but drivers would learn that fact and adjust perfectly to just 1kph below that limit. This would then enrage puritans that would DEMAND that these MURDERES be PUNISHED. Sadly for some reason traffic law is an area of zero tolerance for some.