An awful lot of hypocrisy exists around speed cameras, on both sides of the argument.
Firstly, let's dispel the myth that law-abiding motorists are being persecuted. They are not. Breaking the speed limit is not law-abiding. If I choose to break the speed limit (which I do, when I believe it to be safe), I do so in the full knowledge that I risk being caught and punished. I am not a victim. That said, I do not want to get caught. Nor do I wish to breka urban speed limits. These should be enforced with great vigour, to protect the lives of pedestrians & cyclists (after all, I am a pedestrian as well, and have been a cyclist too in recent times).
The other great source of hypocrisy is that "safety" (i.e. speed) cameras exists to reduce accidents & improve driving standards. They do neither of these things. Speed cameras can do only two things, detect speed and raise money. They do not detect dangerous driving. They do not detect uninsured drivers. They do not detect drivers under the influence of drink or drugs. They do not detect stolen cars. They do not exercise judgement, nor do they educate and inform drivers. The only thing that can do all of these things is a visible presence of real live Police officers patrolling the roads. The problem is that they cost money, whereas speed cameras raise money. It is alleged that the money raised is used to increase visible real live patrols, but experience suggests otherwise.
About 15 years ago, I was driving through an unfamiliar town in the West Country, Salisbury, I think it was. I didn't know my way, & was concentrating heavily on direction signs rather than speed signs. I was on a dual carriage-way through the town, which I believed to be an "urban clearway", which usually have a 50mph limit. I overtook a Police dog van at about 47mph. Moments later, I was flashed by the van to stop. The officer informed me that I had just overtaken a Police vehicle, while doing 47mph in a 40mph limit. I explained the circumstances, and apologised for what I described as a honest mistake. He did a few checks, from which he discovered I was a long way from home, & obviously didn't speak with a local accident. He decided that I HAD made an honest mistake & sent me on my way with a friendly warning to be more observant in unfamiliar surroundings. A speed camera would have fined me £80 & 3 penalty points.
More recently, I was driving through Southern Scotland on a near-deserted motorway, in perfect weather conditions, at 85mph. Nothing about my driving in those conditions constituted a danger to myself or any other driver. I then noticed a mobile camera van positioned on a bridge about half a mile away, so I had to brake sharply to get below 70mph as quickly as possible (those things have a huge range). That sudden braking manouevre probably created a hazard when none had previously existed. About 60 miles further down the road, in much heavier traffic, I was travelling well below 70mph, when a moron in a 4x4 veered across lanes into my path, while gabbling away on his mobile phone. I had to brake & swerve to avoid being wiped out altogether by two and half tons of out-of-control metal. The mobile camera would not have detected that incident as it took place below 70mph, but which was the more dangerous incident?
The only way to improve driving standards is to get Police back on the roads again, but this won't happen while cameras are raking in money for them. If everyone had a detector, revenues would fall & Police would have to revert to proper policing. That won't happen, of course, but in the meantime time, I will use my Road Angel to help me judge when I am at risk of detection.