My Dad told me about a place in NYC in the 1940s or maybe 1950s. It was a lunch counter/bar and grill kind of a place. A stretch of O-gauge track ran across the length of the bar, and then circled back into the kitchen. It carried a train with primarily flat cars. When an order was ready, the dish was placed on a flat car, the train would start up, and the operator would stop the train when the flat car was in front of the respective patron.
I’ve heard of a Hamburger Express in Newark and there was mention of a restaurant in the Parkchester neighborhood of the Bronx where there were tracks on the counter that brought your meal.
In the Cleveland area we had Revco drug stores where you gave your prescription at the front counter and the clerk placed it in a gondola of a Lionel train that ran it back to the pharmacist. Once your meds were ready they would arrive by train back to the front counter.
A few years ago a modeler in the UK had a garden railway. Amongst the rolling stock he had a whisky train that had little (type of) faucet. Each tank car held one shot of whisky. Every so often when he fancied a drink, he would send the train round the layout. He would stop it when it reached him he would pour himself a drink.
Daddy Dee’s Ice Cream Parlor in North Fort Myers, Florida would deliver your order with a G scale train that ran behind the booths for a few years.
Later, they raised the track above the booths. I was told there was a health code reason for it. Something about your order passing by other tables before it arrived at yours.