Accident figures peak.
Council installs "safety" camera and lowers speed limit.
Next year figures revert to mean. Council: "Aha! The lower limit and camera has cut accidents, we'll make it permanent".
Net result: speed camera in middle of nowhere, on a dual carriageway, in isolated section of 40mph limit. Often on a bend.
Goodbye 85th percentile rule in yet another spot. I can see why that's unpopular. Yet the spots that really should have cameras near schools, or in other spots around town, generally don't.