The collective criminal justice systems of America figured out a long time ago that speeding tickets were a reliable source of revenue. At first the American driver fought back, with contested court cases and innovative new radar detectors. After a while, the police ground them down. Now nearly 95% of people accused of speeding meekly pay their tickets without seeking their day in court. Radar detectors are illegal in many of the states that ticket the most, and such enormous population centers as California, Texas, and New York make an average of $150 each off of each person they ticket. More than one in eight drivers will get a traffic citation in the next year. This economic toll fuels the entire American criminal justice enterprise.
Radar detectors have been around since the 1970s, but they reached the apex of their popularity in the 80s and 90s. Since then police departments, buttressed by compliant legislation, have installed radar detector detectors and moved to new systems like “lidar” that cannot be detected by radar detectors or jammed by ordinary methods. Lidars use laser light, instead of radio waves, to measure the speed of a moving vehicle. They can be foiled by specialized detectors or jammers. Ingeniously devised light-absorbing paints, polarized license plates covers, and banks of reactive LEDs can all defeat lidar. However, that is not a cost effective strategy when it is unknown to the driver which agencies have lidar and which have other systems.
Even if the specific speed detection system used by police is known to the driver, the legal liability citizens expose themselves to by owning a detector can cost more than a ticket. Several states have strict anti-detector laws, as radar detectors cut directly into their revenue source. There are advanced radar detector detection systems, so the police can triangulate and home in on anyone using such a device. Windshield mounting of radar detector systems is against the law in California and Minnesota, and there are many more laws besides these. Radar detectors are thoroughly discouraged by the law enforcement community of America.