Thank you for sharing your worldwide experience.
As I said this is a little bit run-on topic and laws are already different from one state to another in the US, not to speak of in the whole world.
Sure enough,there are speedcam enforcements in quite a few European countries,they may be widely used in the roadways there but it is defnitely not popular in the US(suppose it is not out-law).
Normally, there are several criteria that result in a speeding ticket in the US; 1)The driver sped, 2)The cop that in police uniform was present, 3)The location was under that cop's jurisdiction.