The tried the cameras in BC, Canada, for a couple years, then pulled them last year (or the year before). The studies they did showed that they werent generating as much revenue as calculated so they ditched them.
A lot of people took the tickets to court if there was even the slightest hint or blur on them. In fact a years worth of all tickets taken at the start had something wrong with them, so if you disputed them they got thrown out. Of course you had to dispute them, and if you didnt you still had to pay. Made a lot of sense, how much did all the court time cost in disputing them compared to the ones that paid.
The time it takes to get a ticket is stupid as well. When a person gets a ticket, evn a warning, it puts them in a different mind set. They slow down, think over thier driving some more (usually), etc. But on a single trip with cameras, you could get caught 5 times and dinged for them all without learning anything but what its like to loose your license.
Personal law enforcement will always beat cameras. Even with a pig headed cop on a rampage you can still at least attempt to reason with him ;p