My daughter and I are a prime example. We occasionally eat out when she’s working in my town, and we split one dinner salad and a philly cheese steak sandwich. The restaurant knows us and is happy to do it.
We enjoy each other’s company over a meal, say grace publicly, and tip well because the service is excellent.
Many restaurants, including chains like Applebees, will cheerfully serve half portions, some even have it on the menu.
It’s a proven fact that these restaurants will stop offering/selling these items if the customers stop buying them.
Has that restaurant STOPPED offering the full size salad and sandwich? If not, then your example, fine as it is, does not provide proof of SJSAMPLE's assertion.