Tracks form a network that can be used to reach more than just the directly connected cities. Similarly, airports require a high up front capital cost and form

Tracks form a network that can be used to reach more than just the directly connected cities. Similarly, airports require a high up front capital cost and form a network that allows you to reach further than the infrastructure at the starting point allows. On rail having high maintenance cost for the infrastructure: every flight requires expensive and fragile planes + lots of fuel, so the marginal cost of each trip is high. So it's a little more complicated to compare the costs than you suggest.