My guess is that UA does not require or perhaps even train the FA's to show or otherwise pay any attention whatsoever to the wines they are serving. There are a few (very few) who do.

Do anyone know what are UA's requirements for an FA to work a premium cabin? Are there any other than standard FA training? First world problem, but I once had an FA serve me white wine instead of the requested champagne because she saw the word "Champy" on the label and assumed is was champagne. I don't know if she just didn't notice the lack of bubbles or didn't know. (But as a white wine for United, it wasn't bad! )