I’ll express my last bit of disagreement with your reasoning and then I’ll probably leave this argumentation, but I will read if you choose to respond. This is not what cost means, you are basically saying that your gut tells you it should be cheaper without any supportive arguments. If e.g. the train requires more energy to run faster, that alone could make it more costly, even if it has a higher capacity. Since neither one of us seems to have idea of the actual costs of running trains, I don’t think we’ll get anywhere with this!