I also think that the elevation is taken into account for the transport prices.
I have two cities, A and B, and transporting passengers A->B brings me more money per passenger (about +30%), than B->A. There is only one train and a single track, so the distance is definitely the same. Travel time is also the same as the loco is powerful and gains the max speed very fast and maintains it for the whole route.
The only difference is that city A is near the river, and B is quite uphill.
So, I suppose, hauling goods or passengers uphill brings more money.
It would be very nice if developers would actually tell us stuff like that.
