German trains also used to have actual chefs on board, but it proved to be very cost-ineffective. There was even a McDonald's on a train, called the MacTrain: https://www.berliner-zeitung.de/streit-zwischen-mcdonald-s-u...

I've ridden almost all of the long-distance Amtrak lines and not seen what you describe. There are "long stops" where there are crew changes and refill and restock, but they are not primarily for passengers to visit the train station (and through-passengers that wish to get some fresh air are explicitly warned not to leave the platform, though this is not generally enforced if someone wants to take their chances).