Did you know that you can board an airplane with an expired driver's license, but if you try to take an Amtrak train, they will refuse to allow you to board the train? Doesn't matter if you have already paid for your tickets or not, there is no procedure to verify your identity if your driver's license is expired and you have no other form of ID.
For airports, there is a secondary procedure to verify your identity if you want to fly and your driver's license is expired. You probably have to go through a more thorough bag search, but they will get you on the plane and flying to your destination.
How do I know this? I took my first and probably only train trip earlier this year and witnessed a man, his girlfriend and her child (may have also been his child) take the Amtrak shuttle from the airport, ride it for an hour to the Amtrak station where they were to pick up their paid in full tickets and board the train for their destination. They were on their way to start a new life in a new city, job waiting; they just had to get there.
The most disappointed and the one who really didn't understand was the child who had been anticipating his first train ride, pretty disappointing for a youngster (he was four or five), and for no better reason than Amtrak couldn't anticipate such an eventuality even though the airlines did. It's no wonder they have always and will always be attached to the government teat, or several of them.
Being compassionate travelers, we did try to intercede on their behalf, only to be treated as if we were troublemakers ourselves because we brought up the secondary procedure that airlines use and is available online (Iphone internet search). The ticket agent, who is employed by Homeland Security/Amtrak and the local police officer that had been called to verify the expired driver's license, were not very helpful nor did they show the least compassion for the plight of the family trying to get a new start, refusing to make any phone calls (except the one to the police) and almost refusing to allow us to read the directives Amtrak uses to deny travel to US citizens.
Shouldn't the procedures be the same for airplanes, buses, trains and ships? I would think so. Either we go back to the way it was before the "not to bright idea guys" took over writing the procedures for travel, or we standardize them so that no matter what mode of travel you chose, you have to have the same documents or be able to pass a secondary procedure.
On a side note. Being my first train trip, I was disappointed in the accommodations provided by Amtrak. Some cars had 120vac outlets, some didn't, and sodas were served lukewarm, if they even had the flavor you asked for. Really disappointing to order a Rum and Coke and be told it would have to be a Rum and Pepsi, just ain't the same unless you have no taste buds. And some cars had more than enough air conditioning while others were just barely cool enough to ride in. Also they tell you that you can sit anywhere, anywhere they tell you to that is. They group you by destination so that when they get there, the conductor has less work to do because he/she only has to check certain areas to see that they got off. Another glitch in the ride, if they pass through a dry county or a state that has blue laws, they shut off the bar. Try that on an airline flying over the same area and see how far that will "fly".
Basically, in my opinion, Amtrak is not customer friendly, at least not to a first time user or a down and out traveler.