Personally I think that the real issue is that the focus on speed limit compliance in both UK traffic law and law enforcement has raised the perceived importance of those limits far above where they truly sit as an indicator of good or bad driving. Does anyone with a true understanding of the subject really, honestly, believe that travelling at posted limit -1 mph = good, safe driving, while travelling at posted limit +1 mph = dangerous, antisocial behaviour? Of course not. Safe driving is about far more than speed limit compliance, yet that's the message that the anti-speed lobby has tried, and at least partially succeeded, in portraying.
The fact is that people do routinely exceed the posted limit yet do not expose themselves or others to undue risk. The speed limit can be (and should be) an effective proxy that indicates to the driver the sort of behaviour that is expected, but the "slower is safer" school of road safety has resulted in many unncecessarily low limits being introduced. Unfortunately, this diminishes the worth of all speed limits as people routinely encounter these artificially low limits and exceed them with no ill effects (except, perhaps, the risk of points on their licence). It's little wonder then that people feel hard done by when an automated, or otherwise rigid and formulaic, enforcement system detects them breaking a speed limit and they receive a sanction for doing so.
Police officers often talk about the "attitude test" when they stop a driver, and for good reason. Most (perhaps all?) of us who have been driving for many years can probably tell a tale of how we were stopped for speeding by a real life police officer and given a stern talking to and sent on our way. Most of us would admit that a) we deserved to be stopped, and b) we learned that what we were doing wasn't acceptable and that any repetition would be met with some form of sanction. If, however, we adopted the "there was nothing wrong with what I was doing" approach with said officer we would probably have received a ticket. That's not because the officer was on a power trip, it was because they used their judgement to decide whether we'd received the message they were trying to get across or not, and whether or not we would learn from it. Automated "justice" by post can never achieve that, and neither can rigid "it's either black or white" enforcement by a police officer at the roadside.
Properly set, appropriate, speed limits can be a valuable tool to guide safe driving. Couple that with sensible enforcement regimes to deal with those who drive inappropriately and they work very well. However, they cannot ever be the absolute arbiter of safe driving that the current focus upon them makes them out to be. The sooner everyone admits that, the sooner we can move on to more effective road safety policies and look forward to driving on safer roads.
