I know there are mods, but I am convinced that the game should be playable with trains without mods. It may be hard and difficult, but it should be possible once one does it right.
I would expect that buses and trams would profit from innercity connection, and trains would get more interesting on longer intercity connections. But for now, once on start running trains, even with the aid of buses en trams, it becomes barely survivable.
@Killkenny, do You manage to run trains profitable without mod in hard mode, or do you rely on trucks/buses/trams to survive? If so, why not using only trucks/buses/trams?