Food service tipping is a lot different than at Amtrak. I used to manage a chain restaurant where the corporation paid the servers minimum wage but then deducted 50% of their pay as a tip credit, thus base was half minimum wage covering taxes and benefits, therefore the servers were dependent on working for tips. The good servers made good money. In the evenings if they wanted a bus person working their tables they had to share some of their tip money, but a good bus person raised the average tips and turned the tables more frequently. The cooks always received 10% of what the servers received in tips. Now the Amtrak DC servers are making more than minimum wage and there is no tip credit taken from them, so yes they are making much more to start, but their environment is much different, limited hours, moving and swaying car, limited and degrading menu,
In an ideal world, everyone would be paid properly for the job so there would not be the reliance on tipping, thus no one would need to tip, its included in the price you pay.
I have never worked a dining car, and never will unless one comes to Boston on 67/66 or something. That being said, I have been told that service attendants in the dining car are taxed extra based on the total sales of the dining car, to account for being taxed for what Amtrak figures they made in sales. I'm not 100% sure if this is true or not, and I have a feeling Tom would have mentioned this if it were true on Auto Train at least.
I was trying to stay out of this thread, but for what it's worth...when I road 449/49 from BOS-ALB-CHI, I felt bad when both of my table mates left nothing on the table when their experience seems to have been a pleasant one in the diner, and they were both traveling in the sleepers so the meals were "free".
I obviously know what the attendants make in tips, wages, and benefits, but I also know how rough the job is. Being away from home for days, working/serving on a moving train, the lack of sleep in between shifts onboard or sometimes at the layover point if the train is late. Know all that, I left a $10 to cover for the table, and personally thanked them (although my steak was initially undercooked, I had a great first experience in the diner, and the crew was extremely friendly.)
What it all boils down to is this... Tip if you can afford to and it's warranted, don't if if you can't afford to or if it's not warranted. If you can't afford to or you don't want to, at least thank your attendant.
I have always been a firm believer that I make decent enough wages that tips should not be expected, although they are certainly nice. But I have had many passengers who don't tip, don't say hello/good bye (I greet every single passenger who comes up to my counter, mind you), nor do they even say thank you either. That is what really grinds my gears (sorry for the Family Guy reference!)