Ah. So those who said it likely assumed it worked the same as TPF1. I never played TPF1 myself. TPF2 is what got me hooked.
The reason I didn't question it was likely because I thought it made sense realistically. If you transfer to a depot in the middle of nowhere in the opposite direction, who is paying for the goods?
But then there is the fact that there may be more than one industry to deliver to on the map, so how would it know which one is your target?
So yeah, gameplay > realism comes into play at some point.
Passengers also don't mind backtracking if it means they can get on a high speed transport, since they're based on time overall. Hence even if you have an isolated town on water with no roads, the people won't even board a non-hovercraft boat if the destination is too far away. That's one of the things I'm not fond of in the game since I like using passenger boats. Even if you're using a boat line to transfer from an far island, you could be missing out on a number of passengers simply because the slow boat like Klondike increases the time too much even if it lands at a town with a high speed train to get to a farther city.
I guess that's were planes would come in. But... eh. XD