It seems to me like giving them wine is some effort at being more humane. I recall reading recently that the "last meal" tradition in the United States had been removed in Texas, because of the idea that they didn't "deserve" any special final meal. Regarding giving the family what they want, I think that would be an improvement. But they should be forced to push the button/pull the switch/pull the trigger. If they want that kind of revenge perhaps emotional burden should be on them to deal with it after the fact. The forms of execution where no one knows who 'technically' killed the person - a firing squad with one empty rifle, a lethal injection with one inert button - those also absolve individuals from responsibility. If people are going to execute others, they need to own that as individuals. Executions become much more difficult when they aren't abstract, as you said.