The license plate cameras near me simply take a photo when motion is detected and send it to the server or stores it until connection is reestablished. Then they use image recognition on the car to determine the make and model and on the license plate. They also claim that they can record items such as bumper stickers or body damage. I think that they probably have humans review cars that don't match exactly. My guess is that they use object detection to isolate the license plate, but you could probably make one by printing text onto a piece of paper and gluing it onto some cardboard. I also think you could mess with it if you put a decal of a letter or number next to your license plate.