The one plausible excuse that I heard was that we were riding a time machine. We wouldn't be visible to anyone in the scenes (assuming they could see) so have him out there yelling "EXTRA EXTRA" to nothing really wasn't logical, so they turned him around had had him facing the fake street where the towns people might be inclined to buy a paper. It apparently took a number of years for someone in imagineering to notice that idea, but, eventually they did. We think we are on a train, but, we are not, we are on a time machine and would not be visible as we passed by. Since the view through the message office showed a railroad just behind them, I guess that is what the logic was originally. They must have had a good reason because Disney has not ever found it worthwhile to spend money to relocate that particular AA just for fun. That would have been someone's bonus.