Do they sell them to anyone who requests them, or do you need to be wheelchair bound? Do they hold them open until it’s clear no one with disabilities is going to reserve them? There were three on the last Florida train I took, and I don’t think they were even used.
Here is the URL for the accessibility page on the Amtrak website itself:
http://www.amtrak.com/servlet/ContentServer?c=Page&pagename=am%2FLayout&cid=1241267362146