There is a difference between the math not adding up and not liking the answer.But back to your dining car service... what you described sounds a whole lot like outsourcing the dining car operation. There's no way you can charge passengers what it would actually cost to prepare the meals on a long distance train. The math won't add up.
GWR in the UK offers dining service on some scheduled trains between London and the west of England.
The full streak dinner with appetizer and desert will cost you about $60. They get rave reviews on Trip Advisor.
How many meals like that do you think Amtrak could sell?