There's a benefit to bundling a bunch of concepts into a single term, as it captures the wisdom in a way we can communicate efficiently. It's easier to say "train" than "a collection of carriages linked together in sequence, running on rails, for the purpose of..." The problem comes when people try to tell you their car is a train. Or their bicycle is a train. On some other misunderstood definition that misses the key properties of being a train.