[Reposting this response: I accidentally added personal information and CruiseCritic kindly removed the post for me. I may have rephrased things as I don't know where I saved the original text... 😭😂 I added some comments too]
Thanks for your feedback, @cruisetonowhere10 and @princeton123211.
So, Greyhound bus expects you there within 15 min, as border inspection happens in the US side (the country I was traveling to), which to this day has been my only experience with international travel. [Note I did not claim this was an exclusive way of dealing with customs, it's just how it is usually done and how I've always experienced it]
You're right, @princeton123211, Amtrak does disclose on their website that we should be there 1h in advance. That's simply not enough. They should also disclose it in the email they send with the ticket, not with a "for more information, click this link" messaging. I'm not claiming they are being malicious, but if 6 other guests also had the same misfortune as me on that trip alone, this should tell Amtrak the way they communicate this policy is not clear enough. Faulting a customer for not reading fine prints (or in this case, clicking additional links) is NOT good customer service. Offering some customers cancellation and denying it to others is even worse.
In the end, I'm posting this here just so people won't have to go through what I've been through.