This question has come to mind on several occasions where I've been served a plate that is missing a component or has included a component that I've requested to be withheld. Is it the servers' responsibility to know the menu well enough to detect these inconsistencies prior to serving? I think so.
It came to mind today as I was reading another thread about a man and his wife who were served 2 different portions of foie gras. The server (reportedly) said she had noticed the difference, but served it anyway. Why?? To servers: Are you allowed to question the chef/expeditor of discrepancies?
Then there is the issue of having one "team" in charge of taking orders and another responsible for serving. That mid-range chain trend can further exasperate the topic subject.