You can make these cameras so dense that there is very little opportunity for speeding in between two cameras.
https://en.wikipedia.org/wiki/SPECS_(speed_camera)#Similar_s...
https://en.wikipedia.org/wiki/Speed_limit_enforcement#Averag...
(Sorry for the nerdy nitpick)
I heard it does not apply to all cantons, the Italian ones speeding is more OK.
All that being said I really dislike the US system where you can pass a police car driving 75 on the 101 and he doesn't care. There has to be some enforcement of the rules.
The US system is a probable cause generator.