This is similar to SEPTA's (Philadelphia) three center city stations, Market East, Suburban, and 30th street. The stations are so close together, that it makes no sense for the SEPTA conductors to run through and collect tickets between each one. Also, the three stations are sometimes used as crew change points, so at times, there's no one around to even show a ticket to.

Of course, Amtrak advertises this along the lines of...Amtrak ticket holders (arriving in Philly) can travel between the three SEPTA stations by showing your Amtrak ticket stub. It's all in the way you market it.