It is not so simple to "attach" cargo to a train. The train crew knows how many cars the train consists of and there are periodic "defect detectors" that among

It is not so simple to "attach" cargo to a train. The train crew knows how many cars the train consists of and there are periodic "defect detectors" that among other things report the number of axles to the crew. The crew also has a manifest, and eventually they would notice if something was out of place. Individual train cars also have radio tags that are used to monitor their status as they move: https://en.wikipedia.org/wiki/Automatic_equipment_identification https://en.wikipedia.org/wiki/Automatic_equipment_identifica...