So the argument is that they don't control speed, so scrap them. Why not use ones that do control speed? Hands up those who've driven over the limit in an area with "average speed" measurement in force?
I agree that the cameras aren't always effective, but to just get rid of them is a green-light to all the people out there who think one of the following:
a) My time is more imortant than someone else's safety.
b) Going fast is fun, my skills are brilliant so everyone is safe!
c) I'm not paying enough attention to know what the speed limit is.
The majority of these cameras are in urban areas, enforcing speed limits of 40mph or less. I think this a classic bit of pandering to popular opinion, good for headlines and popular with the people who read the Daily Mail. I don't even think that the cameras will vanish, £320k doesn't sound like the total budget required to operate them, only part of it; council funding may well be replaced by money from other sources (e.g. central government, who presumably get the "profits" from cameras).
I love the phrase "tax on motorists" though, as if breaking this particular law is totally acceptable and we shouldn't be inconveniencing anyone who does; fuck it, why not call them "heroes", like the metric martyrs, and give them money?