You can see speed cameras coming a mile away in the UK, I think they were politically pressured to make them yellow and visible to justify their claims about them being a deterrent, despite the protests from sadcase safety groups wanting them to be hidden to catch more people. As a result they're basically a joke.
On a typical motorway in the UK you'll have the furthest left lane with heavy goods vehicles that generally have limiters on them, and people towing caravans etc. doing around 70mph (the legal limit), then in the middle lane you'll have old folks, people with crap cars, etc. doing around 80-90mph (the de-facto limit, only the most anal of traffic police cares about that kind of speed), and then in the right lane you'll have normal people doing 90mph+ Then all of a sudden the entire mass of traffic will start slowing down at once due to the presence of a speed camera, right down to about 70-77mph for a couple of seconds before everyone just as suddenly starts speeding back up. It's utterly pointless, and more dangerous than not having them.
What's getting more common and more annoying are stretches of road with average speed cameras, that record the registrations of all the vehicles entering and then leaving the section, so essentially you have no choice but to drive at the speed limit, otherwise you'll pass the second camera too early to have not been breaking the speed limit. Thankfully they're only really used in places where roadworks are taking place.
I have zero experience with red light cameras, I'm not even sure we have them as I've jumped a lot of red lights and nothing has ever happened. So I can't really judge how they would work in practice.
