Garry
I would maybe take issue with the statement that speeding is a crime, and come to that I feel the same about drink driving, in some circumstances - a crime requires intent, and in some circumstances it's possible to exceed the speed limit accidentally,
Odd that a policeman doing something which has an accidental consequence, is however a crime in your eyes, even when a jury find otherwise.
Anyway, dealing with specifics, in most cars there's a dial or indicator in front of the drivers eyes, and that has numbers on it. It's a very simple game this, you keep the needle on that dial, below the number in the big red circle at the side of the road, and you don't get a ticket. So in simple terms, if you are doing what you should be when driving and paying attention, then you don't commit the crime of speeding. If you can't do that, then you shouldn't be driving.
If you aren't paying attention, or you decide to ignore the speed limit, which lets be totally honest here, we all do, and get caught then no ones to blame but you. Irrespective though, it's a criminal offence, whatever you regard it as.
Anyway, onto your sensible and valid point about detection. Unfortunately, HMG want to spend less on Policing, so that isn't going to happen. Even if that wasn't the case, the public want burglars locked up, muggers off the streets and drug dealers got rid of. Which is the most important? Unless you have plod on ever street corner, they can't do everything.
But the real inequality, which hasn't been mentioned is this. Nick an old ladies last £10, and if you're unlucky and get charged by the CPS, and you then get convicted, you are looking at a sentence of conditional discharge and other low level 'punishment's for the first 4 or 5 times you do it.
Commit a traffic offences and you almost certainly will be prosecuted (or issued with a FPN) which even for the first offence will result in a meaningful punishment, albeit a fine usually.
That is where the inequality needs to be dealt with, what people regard as 'proper' crime should be punished at first offence, not numerous convictions down the road.