Re: a bit like cameras in ATMs
To be fair to the plod, I didn't see anything in the article that suggested that they weren't willing to investigate the crime. After all, they went to see the guy in his premises to talk to him about it. That's more than you get if they don't have the resources to make an invetigation.
From their perspective, I think they were the ones trying to avoid entrapment, presumably because this guy had made some baseless, or unverified complaints in the past. The cop in question, however, was pretty stupid in not informing the complainant that he would be filming him before going into his premises, or asking him if he would agree to being recorded, particularly since he already knew the guy was the sort of person likley to make a complaint against the police - which, lo and behold! He did. A bit of a self-fulfilling prophecy there.
The police have to treat everyone fairly and equally. There are only a few circumstances where they can act otherwise, even with someone they are arresting (for example, if a suspect violently resists arrest). They dropped the ball on this one, and are being slapped for it accordingly. Pretty dumb on their part really.