The UK has this and it's super-frustrating! (aka it works!). With those radar based grey box cameras you see in urban areas, you just have to make sure you wer

The UK has this and it's super-frustrating! (aka it works!). With those radar based grey box cameras you see in urban areas, you just have to make sure you were not speeding when going past them (they even put handy calibration marks on the road to help you notice them). But the average speed ones have overhead cameras that read your license plate every 5-8 miles so you have no choice really but to stick to the speed limit (I have no idea what the margin of error is). Driving from Inverness to Edinburgh (A9 I think), they are quite frequent. I feel a little cheated really, in the US it's you vs the state trooper, they have to see you to ticket you. You can almost always get away with 10 over on the highway and on a familiar road you usually know where those crossovers that they hang out in and Waze is pretty good at reporting cops in near real-time. Even if you end up passing a waiting cop they won't stop you for 75 in a 65. I'm pretty sure you'd get a ticket every time for 10 over in the UK!