The problem with private sector choo-choos is that there's a train from Washington to Baltimore to New York.
How many different sets of tracks are there? In order to promote efficient service, there has to be
enough traffic to be commercially viable.
more than one service provider.
Generally, there's not more than one or two sets of tracks going from point to point, not any more.
Do competing companies share the track? Why bother?
So, the basic problem with rail is lack of competition and yet, if there's only one company running trains from A to B, because only one can afford to run, sure enough, there'll be a mob of dimwits whining about "monopoly".
Could be that no one in the private sector, given all the controls and regulations and other hassles, wants to run a train that way. So the government volunteers, except governments do not excel in passenger service, no. The forte of government, after all, is power, and force, and threats.
Fortunately, the United States is no longer linked by passenger rail as the only long distance means of mass transit.
We've got airplanes.
Which suck even more of the passenger base away from the choo-choos.