There are some extremely widely held ideas about what kinds of rail travel are viable. At this point, everyone recognizes that the Northeast is a reasonable place for trains; passenger rail has been so successful that the best efforts of a wide variety of individuals and interests with widely variant motivations were unable to kill it off entirely or even to privatize it (altho goddess knows they gave it their best shot). This is sort of amazing, given that Amtrak's mission was never commuter rail per se -- that was preserved by the individual railroad companies for themselves. They handed over the national passenger network. It should not be surprising that Amtrak's current success is attributable largely to a focus on commuter lines (albeit inter-city commutes aka exurban commuters, and a fair amount of people commuting via rail to where they work for state government from where they live: Sacramento to SF, Albany to NYC, Seattle to Olympia? Don't know about that last one, actually) and a removal of the _mandate_ to maintain a national network.
It shouldn't be surprising, but it is.
What's really interesting is digging through the breakdown by state Amtrak info (State Fact Sheets, click on News & Media on the bottom of the page at Amtrak's web site) it becomes clear that Amtrak is _not_ funding the new cars, additional sidings, etc. that is making those train commutes possible. I first noticed that Vermont owned track and maintained it. Then R. said Illinois maintained track, and now it's looking like a _lot_ of states have taken over track. The amount of money that the State of Washington is plowing into Amtrak Cascades compared to the amount of money put in by the federal government is eye-popping. Compared to asphalt roads, still tiny (roughly a 2 latte a year habit for everyone living in the state, unless I screwed up the math in my head).
So if you live somewhere and you're trying to figure out why trains aren't being developed on lines that you think would be wildly popular for commuters, especially lines that could serve several small cities and/or large towns and shift exurban people from cars to trains? The blame should probably go to your state government. Because where it's working, it's not the feds making it happen. And it _definitely_ isn't the freight railroads going out of their way to be helpful. Quite the contrary.
Oh, and rail bloggers who screed about how Amtrak isn't restoring service from New Orleans to Florida? Amtrak isn't restoring service _anywhere_, unless a state government is willing to fund that service as well -- to the tune of 5-10X the amount of money, committed over a period of at least a decade.