CsC,
I think you have hit the nail on the head with this post, as far as the UK is concerned. In the UK, the Home Office are the central government department who look after the police and the CAA look after aviation safety. The CAA have managed to get themselves into a position where no one is looking over their shoulder, so long as they do not require money from central funds and an airliner does not crash into Central London. In large measure the 2 of them don't really coordinate or integrate their decision making. The CAA just ask for ever higher standards, without really (IMHO) looking at risk at all. In the grand scheme of things police aviation is a tiny part of the HO's area, and there is precious little rigid audit or assessment of police aviation performance at the moment, never mind alternatives.
Essentially, the question never gets asked.
From the views expressed by (most) of the UK police pilots on this thread they are rigidly against any such "blue sky" thinking, so the workforce are not going to be pushing for change either. In a sense you can hardly blame them - as an individual who would not rather fly a twin with lots of technological assistance than a basic single?