Triley, perhaps you could enlighten us as to what Amtrak tells the attendant about offering complimentary service in Business Class . I have never been informed on the train that I could have a complementary drink when in Business class.
I'm an LSA, so I can only speak to things on the Cafe side of it, really. The conductor/assistant conductor is suppose to make a local announcement in the Business Class car to the effect of your comp beverages, and since I'm never outside of the Cafe, I can't comment on if it's done in practice or not. As far as when you come to the Cafe, I have people get upset when I tell them it's $2 for a coffee. I'll frequently get, "Well doesn't Business Class get drinks for free?!" Well yes, but I have up to nine coaches on a train on the NEC that I'm worrying about, I have no way of knowing by sight that someone is Business Class or not. (Of course this was different on trains like 67/66 when we had the split Cafe.)
As far as what you are entitled to, as I say, "None of the good stuff." So no alcoholic or premium beverages. You are entitled to water, coffee, tea, hot chocolate, juice, and soda. I will also do milk if you ask, and even though you're not entitled to Perrier, I am more than willing to do club soda as long as I have an ample supply. So if you come up to me at Back Bay on 67 (where for the whole round trip we only get 2 club soda) and you ask for one, I won't be able to oblige, because it is really meant to be used as a mixer for liquor.
Seeing as you're from Mass as well, and I'm not sure if you're talking about the stepchild of Boston services, the Downeaster...I have no idea how they handle Business Class, as the Cafe car is contracted out on that service. I have only taken it from North Station to Woburn twice (don't anyone try to do this! Tickets are not sold between those city pairs, I was only able to ride by showing my employee ID), and only once did I even enter the Cafe car, to actually talk to the attendant. It was winter of like January 2015 and we sat in North Station for almost an hour before being cleared to depart, due to signal/switch issues. She never went in to the Business Class section while I was onboard, so I would be inclined to imagine you have to go to the counter to get your beverage? I'm sure someone has more experience than me with this.
Edit: Removed the quote tree from my post.
Edit 2: Added bit about Downeaster.