passengers/stuff earn more money depending on the distance they travel. and even more is earned depending how fast they got there. and even MORE is earned if they were more efficient (meaning less is lost while things wait at a station)
i use to have a circle of track around the world. where trains would pick up from one place, to "drop off" (not deliver) to another station. while more trains pick those up to continually drop off at further stations.
till 20 stations later you have like a million people awaiting to hit the final train station. where most of them traveled 20-70% across the length of the map.
a single full load can earn you $1.5million, and can be delivered every 6 seconds with a large enough track system.
but stuff like that takes a very experienced track builder. you need a double 1-way track system in all directions, with tons of proper signals. you need to be able to have trains pulling in and out of every station at like 50 per minute without waiting.
