>the UK and Chinese CCTV networks comes to mind Minor nitpick, but the UK doesn't have a CCTV network. It has a huge number of privately owned CCTV cameras and

>the UK and Chinese CCTV networks comes to mind Minor nitpick, but the UK doesn't have a CCTV network. It has a huge number of privately owned CCTV cameras and a relatively small number of CCTV cameras operated by individual local authorities and police forces. The privately-owned cameras aren't joined up in any useful way and are often of very poor quality; the publicly owned cameras are overwhelmingly used for real-time monitoring of busy city centre locations. Installing CCTV cameras is cheap and easy, but usefully monitoring them is expensive and difficult, even with whizz-bang CV algorithms. I'm deeply sceptical as to how useful any state-level CCTV network would be for mass surveillance. 20 million 4K/30fps cameras would produce something in the region of two exabytes per day; just storing that data would cost about $7bn per month.