I live in a reality based world where I have used Amtrak when going back and forth to college in MA and over the more recent years, watched them attempt to fix the Amtrak infrastructure here along the NE corridor, which is supposed to allow "high speed" - notably for the Amtrak Acela train. But because the tracks and train bridges are in such poor condition due to lack of money and maintenance, the Acela can only go at those high advertised speeds for certain portions and the rest of the time, forget it.
See this - http://www.realtransit.org/nec7.php
During one of our last heatwave with triple digits, it impacted the switches and overhead wires for those trains and that killed them right off for hours and hours. And even during this past July 4th holiday weekend, one of my nieces was trying to get back home on Amtrak here to Philly from Boston and was delayed for hours due to the heat problem.
Then there are the "right of way" issues where Amtrak has to wait for the freight trains on shared tracks and the local commuter trains have to wait on Amtrak on those same shared tracks.
Don't forget that most of those existing tracks are "privately owned" by the freight companies like Norfolk-Southern and CSX, etc. and if feds attempt to take that over, well... 
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