Never say never. But the trailers do come with locks, so that someone can't attach the hitch to their truck.
If you want to take a step further, you can remove the wheels from one side and put locking bolts on so that no one can replace the wheels. Many new cars today come with locking bolts so that the tires won't be stolen. Just imagine this the other way around. Take the tire off, put the bolt on, and no one will be able to fasten a wheel to the trailer.