I think you’re asking too much of artistic representations to always be historically or biblically precise (unless that is the stated purpose of the picture or other piece of art). Most are trying to convey one or a limited number of truths about the event being portrayed. Da Vinci’s Last Supper, for example, focuses on the moment when Jesus announced he will be betrayed by one of his disciples. It is alos worth noting that Jews in Jesus’ time did not sit straight-backed around a table for meals; rather they “reclined” on their left elbows and took food with their right.
The scriptural accounts mention only Jesus and his apostles, but as it was a borrowed room, we might assume that members of the family that lived there might be present or at least in the house. Also, SOMEONE (probably the lady of the house or her servants) had to cook and prepare the meal, and men didn’t cook much in those days (this was pre-Emeril).