In my opinion, it should be 18, because once one is 18, he becomes a full adult and has the full rights and responssabilities of a US citizen. If he can vote, he can ride a train unaccompanied.
The only problem is that your post doesn't explain why the age of eighteen is unique in your view. You're simply walking your logic backwards from an age somebody else picked that was itself entirely arbitrary. By the time you reach 18 you're expected to be more or less self sufficient. The only major exception I'm aware of at that point is alcohol. Everything else is up to you. Where you live, what job you have, what college you attend, who you have sex with, and on and on. We're talking about decision making abilities that are far beyond anything you're likely to need just to board, transfer between, and disembark a passenger train. I'm not aware of any other democracy that has an 18 year minimum age for leaving their passengers alone. The countries that would continue to restrict movement at that age are places like Burma and Saudi Arabia. No thanks. We once had a reputation as the Land of the Free and I suggest we start acting like it again. All this increasing nanny-state nonsense doesn't really make us all that safer. It just makes us look like we can't handle reality.
Hear Hear!
Earlier in the thread, I commented that Amtrak's role here should be in protecting other passengers from the bad or irresponsible behavior of UM's. If a child is not old enough, or mature enough, to reliably sit in a seat, then s/he should not be allowed on. Not because the railroad is a better parent than other parents, but because it has an obligation to its other fare-paying passengers to make their trips comfortable. The same logic leads to removal of drunk or obstreperous passengers.
In this light, we all understand an age restriction. 6? Sure. 8? Though some children could travel at 8, there would be a significant number who could not. So, OK, 8. 10? Starts to get shaky, in my view, but we clearly need to compromise with each other, so, 10. Beyond that, this gets silly. A 12-year old can understand a simple instruction. The railroad, a common carrier, is not responsible for him: his parents are. If they put him on the train, and it doesn't work out, the railroad is only responsible if it acts badly. For instance, if it throws the UM off the train
en route in a place the UM does not know. Like, um, Centralia.
In a crowded society, we often "have to" tell each other how to behave. No, you can't play your boom box in a movie theatre, or start a mouse colony in your apartment, or park your car in the middle of King Street. But this is because your behavior bothers others. Your liberty is constrained where it bumps up against those of the people around you.
But it is sanctimonious for people (or Amtrak) to tell others how to behave "for their own good." Until further notice, American society accepts that parents are responsible for their children, and better able to judge what is good for them than is government (represented here by Amtrak), even in some very extreme cases. If we were concerned for other people's children, as a society, would we not ensure they were given meaningful, fact-based educations, health care, and fed properly? Well, we don't do any of those things. So, we are probably not much concerned with other people's children. Even if you, personally, are, dear reader.
Moreover, our society routinely punishes children for their parents' behavior. Think of the states attempting to restrict education for 7-year-olds because their parents are illegal immigrants, or the termination of one or another benefit to single mothers, rendering them (and their children) homeless, because "she should have known better." Perhaps. But her child?
Well, we don't care about her child. We treat the parent-child couple as an indivisible unit.
So, to all of you trying to "help me" by insuring that I drive my kids to where they are going, instead of putting them in the far safer environment of the train, please explain: how, exactly, is this your concern, or the government's? As a parent, should this not be left to my daughter and me? Or, am I missing a point? Am I somehow bothering you (other than offending your sense of order in an abstract way — you can get help for that)? If I am, I perfectly respect your right to tell me what to do. Otherwise, not so much.