As it turns out it doesn’t actually cost that much on regular transit, there’s an AIRPORT SURCHARGE because it’s an “airport train”.
No wonder Americans don’t use public transit, even when the system exists it’s ridiculously difficult and expensive to use.
https://en.m.wikipedia.org/wiki/Capitalism
In the context of “Why do Americans think everything has to profit?”, then the point is that the train is considered only for the profit it can make, and not for the environmental etc benefits. This is a result of the market economy as you rightly state (and private ownership of transportation).