Wasn't there a push once upon a time to get coach patrons to eat in the Dining car to limit their losses? I hate to be the one asking this, but if the diner is really at capacity shouldn't they be breaking even? Even just on paper since sleeper food service is "already paid for".
Some countries treat food on trains like an amenity and don't seem too broken up about losing money on it, but I don't get how if you're stuck on an LD train and it's either eat out of your own cooler or buy Amfood that Amtrak can't seem to get it right. Didn't Pullman make money back in the day? (Of course their pay was bad.)
I understand that short distance trains will inevitably lose money on food but it's often a "loss leader" to boost ridership. Commuter and state-supported routes often keep them because the public demands it. VRE even had a cafe car until they had more riders than they knew what to do with and at that point they got rid of it and put in more seats.