Dave
Yes, its true, there are less Traffic Police now, but then thats not entirely the fault of speed cameras.
In theory, although there are less Traffic officers employed there are more available. Yep, I kinow sounds like faulty logic but it's not.
So, pull up a lantern and swing a sandbag.....
When I was a baby police officer, and had no option but to report people for traffic offences, rather insultingly occasionally they would plead not guilty. So off to the local Magistrates for an afternoon hearing. And interestingly the court would be full of Traffic Officers. Why? Because all the people they reported unsportingly pleaded not as well. So it'd not be an exaggeration to say there were more traffic officers in Courts than there were driving round the streets.
Now, all that changed with FPN's for traffic Offences, and suddenly, far fewer Police of all flavours in courts.
That was used as a justification for reducing traffic numbers overall, but it also mmeant there's probably no fewer on the streets.
Anyway, Traffic are a bit irrelevant, all Police Officers have the same powers, and especially those who want to go to traffic tend to make themselves busy in that direction.
I have to say it was rare for me to report someone for a traffic offence when I finished my probation, I preferred crime. BUT, most crime had a vehicle involved somewhere, and RTA offences are always a good starting point to stop cars. Ok, that meant in my case that there were mostly warnings for the traffic offences, but the effect was probably much the same.
So in short, your theory, while apparently well founded isn't quite as certain as you clearly think.
As for speed limits and 'greedy partnerships'. The 2 things are separately decided. The Council make pass speed limits, the partnerships not part of that. However, they will act on Police advice, and if that is that a new speed limit isn't being taken notice of, it's obvious where the cameras will go.
If you mean fixed cameras, then the same thing applies I mentioned earlier, the warnings are all there, if people can't see them, they shouldn't be driving at any speed, let alone above the limit.