On the Memphis highways they make a point of sitting on the side of the road and pointing the gun. I guess it’s more for show.
The “gun” they are pointing is probably lidar, which is a laser they bounce off specific cars and is extremely accurate.
Radar And LIDAR are two different devices. LIDAR is hand held and target specific. You look thru the lens at the target vehicle and the device shows the speed in the viewfinder. Pull the trigger and it freeze captures the vehicle picture and the frozen speed which can be shown to the violator.
Radar is not target specific and requires the operator to,identify the fastest moving target. The radar will record the speed in either direction, stationary or moving, all the Officer has to do is correctly choose the speeding vehicle.