Bit of a shame joe public's never informed of the reasons, because without, it simply appears like apathy.
You're right, people are quick to complain when it appears the police aren't interested; but by the same token, hearing "There are reasons, but we can't possibly tell you / you wouldn't understand" also get's very boring.
I've never heard those as responses, thats not to say it's never happened, simply it's not as prevalent as your point implies. I'd always happily explain why we didn't fingerprint cars, it's very easy to show them the reasoning, all you have to do is look at the surfaces, almost nothing is smooth, the windows, mirrors and the plastic covering the instruments and thats about it. everything else has an uneven surface, and you wont get a mark lifted from that which will stand comparison or a defence cross examination. Not only that, but of course a car inside is covered in prints on prints on prints (where they can be lifted), it looks like a spirograph gone very seriously wrong. So even if you find a print, it's usually useless.
The problem is nowadays too many people have watched CSI Bognor, and think it's oh so simple, I mean they can solve it in 45 minutes. Leaving aside half the kit they have doesn't exist, Mr Bad Guy watches the same thing, but as a training film. They know what you can get from a crime scene and what you can't, probably better than I do! Of course the real world isn't like that.
I have given evidence in court on both fingerprints, DNA, and other contact trace evidence recovered from Theft from Motor Vehicles like this and many other serious offences over a twenty year period.
Really? So no negative Interview under caution to go with it? If so you are the only person in the UK thats had a successful prosecution on it! A Solicitor straight out of Uni, with no experience would make mincemeat of that, unless the defendant was stupid and pleaded to it, and if that was the only evidence and he did, then he would deserve everything he got!
The CPS would never go with that, and nor would I! Whats more, I wouldn't go with that evidence alone for a theft from Motor vehicle when we made charging decisions. it's doomed to fail.
I think you are misrepresenting the CPS Guidance as well. They are not saying that all thats needed is a forensic match!