I'll take this one!
Linguists tend to fall into two camps:
proscribers, who attempt to use logic and precedent to determine what is correct, and
describers who merely observe and are fascinated by the way language evolves. Both sides have a point, but proscribers are always fighting a losing battle because language is a living thing and no-one owns it.
On the subject of 'train station', Michael Quinion - a highly respected linguist and, as if that wasn't enough, a railway preservationist, has written a comprehensive article on this and related topics which you can read here:
http://www.worldwidewords.org/articles/trains.htmHe concludes:
Until recently, as I said, the almost total separation of terms between British and American English would have applied also to train station. But it appears that the term is relatively new even in the USA, where railroad station was once the norm. But train station is old enough there for us to be sure of the direction in which it has travelled, and vigorous enough to oust the older term. Perhaps its introduction followed the logic of one of my younger staff. When I pointed out some years ago that she used train station, she replied that of course that was the right term: she caught a bus at a bus station, and so she would expect to board a train at a train station. Obvious really. Why didn’t we all think of that before?