I'm a 100% supporter of getting nice trains throughout America, but trains are relatively expensive for long distances. I don't know why, but if you compare ticket prices (globally!) its often not cheaper to take a train. In my experience, trains are a superior experience, and worth spending more on, but generally not cheaper. The ultra-low cost airlines (especially outside the US) are really hard to compete with on price.
For example, the Shinkansen in Japan (which I totally recommend!) is usually over $100 USD. Which is pretty similar to a flight price. This pattern repeats in Europe as well.
My friend just traveled London -> Edinburgh in the last few weeks, and found the train 2x the cost compared to RyanAir or EasyJet.
Even in the US, this pattern holds. Seattle -> LA costs $50-150 by plane, depending on the airline (3hrs). By train, it's 35hrs and $150. Its a lovely train ride, if you have a weekend to dedicate.
Why should we? The difference is a drop on the ocean for the climate. While choosing convenience/price has a immediate impact on yourself.
The rational choice at the individual level is not to care for such things. Actions has to be taken at the political level.
