Non-marked employees

Hello, I don’t know if this is the right forum for my question at all. I’ve noticed for a long time that at 3 different gas stations, in 2 different cities, the employees take off the license plates on their cars. They come there in the morning, take off the license plate and put it in the trunk. In the evening it’s turned on again. The cars are in a camera-monitored area. The license plates are hardly stolen. I’ve never heard that h Is there any other reason, or is that just to prevent theft of the license plates?