That's it right there in the picture to your left. It's a little bench under a sign outside a convenience store. The Greyhound will arrive a couple of times a day and pick people up and drop them off. You can tell that the bus is about to arrive because there will be people milling about. Depending on how big the bums of the passengers are, this bench can accomodate anywhere from two to three people.
This isn't a very convenient arrangement in the winter, so people usually go into the store where they stand around under the watchful eye of the proprietor. I wonder how much inventory he has lost over the years. The arrangement probably is worthwhile to him because people often ship things via Greyhound, and he does make some money off of that (I hope).
If somebody wanted to take a bus to Toronto International Airport though, this wouldn't be the place to come. CoachCanada handles that, and their terminal is the Howard Johnson's on Front Street. It's much easier to mill around a hotel lobby inconspicuously and not feel like an inconvenience to someone trying to do their job.
One would think that a town of Trenton's size would have a proper bus terminal, but I suppose that the law of supply and demand dictates otherwise. Maybe an arrangement like this is all Trenton needs, however, it would be nice to have a place to sit inside while waiting for the bus in the winter.