Maybe in US…
From where I am, they are 100% slowing everyone down. In fact, so much that I am getting annoyed by that. Thing is, people will go 60 in 50 zone, then see a camera sign, slow down to fucking 40, roll pass it and then pedal to the metal back to 60.
Easy optional solution how to make people actually slow down on the camera: make fine indexed. If they earn a ton, they get a huge ass fine. Say 5% of a monthly income. Stacks to 50% if they are a serial rule breaker. That way not many will speedup.