Upvote:6
The seating policy page in Amtrak's website says:
- Each passenger paying a fare will be entitled to a seat, to the extent coach seats are available.
- Passengers are entitled to one seat per fare, to ensure other paying passengers are not excluded.
- .....
So, basically they do this to allow more passengers to board. In addition to that, they offer multi classes, one can simply by a ticket for a higher class to get a better seat. You can also upgrade after boarding if there's an empty seat in the higher classes.