Happened to me once in Cedar Rapids, Iowa a few years ago. I normally do not speed, but just wasn't paying attention at all. Lesson learned.
Ever since, those signs "photographic enforced" or "electronically enforced" jump out at me.
And I STRONGLY disagree with the OP that this is a money maker. It might be generating revenues off the backs of people who are blatantly disregarding the posted speed limit, but I'm sure everyone driving the roads can see plainly posted speed limit signs and also the warning signs that the speed limit is posted in plain sight. It would be a "trap" or a "money maker" if the speed limit signs were conveniently hidden or obscured, but they are not! YOU ARE A BLATANT law breaker if you are speeding!
Regardless of YOUR opinion what the speed limit should be or how fast you want to drive, speed limits are posted for the safety of everyone on the road. It's not just the traffic directly in front of you or behind you. The people who make the decisions to post a specified limit have studied the situation out on a specific road and made a determination what is a safe speed to safely stop in the event something were to happen. They take into account the side roads entering the main road, the number of private and business properties, how many driveways, access points, children in the are, and any thing else that could potentially jump out in to traffic. They take into consideration hills, dips, curves, and how visible the distance is ahead how log it takes to stop within that distance to determine the speed.
Yes, I HAVE been through stretches of road where the speed limit seems to change every 1/4 mile. I try to respect that, because it's quite obvious if the speed limit is slower than the normal 55 mph, there's something on the road that needs my attention. Yes, it takes a brain sometimes, something far too many do not use. They think "they" are the exception, and "they" are the ones the laws of physics (and man) don't apply to them.
Regardless of what folks have said on these forums, changing speed limits, (regardless of how often) on a specific stretch of road, is for safety reasons.
You also have to remember, that different stretches of the same road could be under the jurisdiction of different law enforcement agencies, ... county, state, city, federal ... all within short distances of each other, on the same road. This also could affect the reason for changing speed limits.
The bottom line is, if everyone actually OBEYED the posted speed limit, there would be no reason for photographic ticketing!
Like I said ... I ALSO got a ticket photographically in the past! AND I support it! I was at fault, I blatantly disregarded the "law", I deserved the ticket. And I'll say it again.... I support the electronic photographic ticketing process. If it gets folks to slow down, pay attention, and it saves lives, it's well worth it!