Anecdotes from other palces…
In NZ for speed cameras they were sited at accident black spots and the tolerance was set somewhere around the 80th percentile. So say the limit was 50km, 80th percentile was 65…at 63 you wouldn’t get a ticket (but maybe a warning)
For the police, I was always told that flashing lights to warn of speed trap was illegal (but not sure of the veracity of this, neve checked to see)
Would imagine that flashing lights to warn of speed trap would be obstruction of justice?
I was driving in Malaysia over the weekend, was flashed to warn me of upcoming accident (closing two of the three lanes on the highway)
I believe the fear of getting caught is what keeps people somewhere near the limit on good highways, if you remove that fear / uncertainty of a cop being present it would have a detrimental effect on overall speeding rates (i.e - if I KNOW there’s not a cop ahead I speed more). By the same token, a ticket is supposed to be a “punishment” - so helping people to avoid “punishment” for their “crimes” can only lead to more crime.
I put punishment and crime in inverted commas as I don’t want to comment on the usefulness or appropriateness of specific speed limits or speed traps