"Some choose to break that law, and are therefore properly caught by cameras."
Well here in the grand old land of Oz and more specifically, the state of Victoria the margin between the speed limit and what legally constitutes speeding (2km over) is less than the margin for error legally allowed in car spedos (+/-10% for all cars made before 2006)!
Doesn’t that seem at all unreasonable? Especially since the speed cameras aren't all that accurate... near my parents house one clocked a bus traveling up-hill in peak-hr traffic at 90km/h. They did a test with the same bus and empty of passengers with no traffic it couldn't manage to climb the hill at more than 45km/h. The only reference I can find at the moment - http://www.roadsense.com.au/fightforjustice.html search for the phrase "STA Bus" for the relevent paragraph.
Like Steve, I also think the solution is more traffic cops - as you said "The more 'revenue generating' from criminals, the better." and wouldn't having someone out there who can police all manner of bad driving help with this?