But that also have its own problems:
- What happens with that revenue over time… will it get smaller, for the same speed, or stay the same?
- How to justify that newer vehicles cost more and older ones just disappear, even if I would prefer them at their price?
In real life, I guess that it has a lot to do with competition: I want some coal for my factory, and I have to order some. I will pay more or less the same for transportation speed, being the main issue the cost of coal itself. But that would mean a deeper economy simulation, with a coal market, a transportation market, etc. If there is no competition and I am the only to bring coal at 60 kph, they will have to take the coal at the price I ask.
Mail and passengers is question apart.