In my jurisdiction, photo citations are reviewed by a police officer (usually somebody who screwed up and is now chairborne) and are subject to protest / due process procedures. The rare, bonafide excuse (medical emergency, chased by T-Rex, dog ate my speedometer, etc.) will often result in dismissal, as will any other reason accepted by the hearing officer (more of a referee than a judge). If they cannot identify you from the photo and you swear under penalty of perjury that it was not you and that someone mysteriously took your car but you do not know who it was....you MIGHT get by.
When I stop a driver, I am required to ask things nowadays we never had to ask in the old days in order to minimize drivers crying foul in court. Now I have to ask if there is a reason WHY they illegally turned or ran the red light or exceeded the speed limit or ran over 12 nuns at the intersection. I have to ask if they have a medical condition...and I have to resist the temptation to ask if terminal stupidity is the affliction. I have to ask if there is a mechanical problem with the vehicle, like a lead diver's weight on the gas peddle. I have to ask if there is any other reason why they did what they did..."Do you know who I AM?" does not count.
Out here on the left / west coast drivers have every opportunity to explain their plight when pulled over. The range of excuses and responses are so satisfying that it compensates for our low pay...often it is a test of self control just to not laugh my ass off at the driver for a great BS alibi. BTW...often the funniest, most outrageous, crazy lie will get a driver off with my reply being, " You, sir (or ma'am) are clearly a master at prevarication but because you otherwise were cooperative and your paperwork is in order, I'll let you go with a warning."
Out here, too, the company that builds, installs and maintains the photo traps takes a cut but at least cops are in the loop and you can ask for a hearing. It DOES help with safety. People know where the traps are, usually at particularly hazardous intersections. People who blow a light see the flash going off. I would disagree with the system if they do, in fact, shorten the yellow timing or otherwise play dirty with the lights.
Driver's who put covers over their plates, over tint the windshield, try radar / laser/ etc. countermeasures, activate force fields or cloaking devices usually don't succeed, at least not often enough to make it worthwhile (admittedly, out on the freeways, etc. some detectors may help). Out here, covers on the plates is a violation but radar detectors are permitted. There were even folks who tried to use military stealth technology and materials to beat the system. They covered the hood and trunk area with echosorb or used radar transLUCENT (not transparent) materials to build a trunk / hood thinking that if it was good enough for the stealth fighter it sure would beat Smokey and his handheld radar. Trust me, even if you beat the electronics aspects usually the cop's Mark One binary organic optical receptor units will get you.
Lots of folks "get away" sometimes or most times but seldom all the time.
Some cops consider the automated citation devices competition. If we have to compete with a machine to meet our quota, how are we gonna' get enough points to score a microwave or plasma TV?