Canada

One of the first speed cameras I remember in Belgium was just behind the crest of a highway. Drivers would give more power to drive up the hill at the speed limit, they'd cross the crest and that same power would make them overshoot the speed limit. So they put a camera right there to maximize the fines. Without the camera there was nothing special about that spot, but with the camera there were a lot of front end collisions. Fine revenue was apparently more important than safety.

Placement of new speed cameras has gotten more sensible with time fortunately, but those old speed traps are still left in place unfortunately. For highways we now have a lot of average speed tracking and that has really improved the flow of traffic. And for villages/towns, there is often a clearly visible lone camera box at the beginning of the low speed zone, those work so well that there is often no camera in them, just the box is enough.