So why are some people advocating high speed trains?
High speed trains are hugely expensive to build and operate. People with money fly, people without take the bus. In between there is the car. There are some places where high speed rail makes sense. New York city is an example of a place where air travel has achieved saturation at certain hours. Bigger planes may be a solution, but they also require longer separation times between landings.
However, you may have noticed that New Yorkers are going to many different places. You can't build high speed trains to all those different destinations. But taking out some planes that are flying in the Washington-Boston axis makes sense. If airports in New York become really saturated, you might even see some New Yorkers flying out of Philadelphia and Boston. The Accella train is still expensive for the federal government, but presumably people waiting on Newark's tarmac are willing to kick in some tax dollars to not hear ("there are 98 planes waiting before us").
But high speed rail means higher taxes. Unless you build a high speed line instead of an airport or instead of widening a major highway, they hardly ever make sense. And in the case of highways, encouraging people to take the bus (with tolls and higher gas taxes), is significantly cheaper. If fact, it requires no tax dollars at all for the same increase in transportation capacity.
For example, there is less than one bus per hour between Los Angeles (pop. 18 million) and San Diego (pop. 3 million). The 193 km journey will cost you $18 and you get there in 2 to 3 hours. That is 9 cents per km. The prosed high speed rail line will actually make a detour via Ontario and Riverside and will therefore take at least 1:20 . The ticket price is yet to be determined. But I'm going to guess it will be more than $18.
In the UK they have significantly lower income taxes (but slightly higher sales taxes) and they manage to offer essentially free medication and dental to all. I'm just saying.