> The airlines are critical to a big country like the US when our passenger rail networks are so slow, so the government supports it.
How does this follow? If they're critical and highly subsidized, that implies the value that people get out of tickets is much higher than what they're paying, so people should be willing to pay much higher prices if subsidies are ended.
They are critical because of the lack of practical alternative means. There is no train rail system that reach the same level of coverage. Even if you forget about the price and time, there isn't a usually route using rail system for most A-B points.