It plays a massive role for logistics. A compatible gage means you can transport a train by train. It’s quite common to even transport underground cars on tram

It plays a massive role for logistics. A compatible gage means you can transport a train by train. It’s quite common to even transport underground cars on tram networks if they exist to bring them closer to the destination. Sometimes tram networks are even completely connected to subway lines to allow trains to go on and off without lifting.