Commuter railroads are usually set up to serve "traditional" 9 AM - 5 PM M-F workers.
This is completely off topic, but every office job I've worked started at 8:00AM. Depending on your seniority you might be able to show up an hour late without any repercussions but the job itself was always considered 8-5. 8AM to 5PM equals nine hours, minus one hour for lunch equals eight hours, times five equals forty hours. Does a 9-5 job pay you to eat lunch or are you supposed to eat at your desk while working or what?
I guess that's what I've seen in popular culture as the norm. Any job that I've had with "standard shift" hours has started at 8 and ended at either 4:30 or 5 PM, depending on whether I took a half-hour or hour lunch.
I wonder if it differs based on time zone, actually. Maybe those in the Central time zone start at 8 to match up with a 9 AM start time on the east coast. No clue if that has any basis in reality or not.