The Door Clearer
He knows he's not made out of make believe. He's a man made from solid man-matter. And you can't walk through that. It's just science.
That's why he stays well out of the doorways - so other passengers can board or disembark with ease.
In fact, this legend moves right into the carriage to fill the empty spaces. It's almost as if he's playing a game of tetris on every trip.