That's just an artful aside; he then brings us back to the real reason he's bringing it up, which is the transit system pattern rather than the station itself.

That's just an artful aside; he then brings us back to the real reason he's bringing it up, which is the transit system pattern rather than the station itself. (And, the transit system pattern is not uncommon but also not quite universal either, so he went with the specific example he knew of from where he was from, I'm guessing.)