In most cases, I would agree with this. But, as I posted in another thread about my experience with this sort of thing. My husband is a diabetic, we were on vacation, and going to another restaurant would not have gotten him a meal any faster.
I think we SHOULD have mentioned the diabetes thing to the hostess, and if they kept seating famblees before us (when WE were there first), asked her how they would like to be sued if DH's blood sugar dropped down so low that he passed out, right there in the waiting area.
If we ever find ourselves in this situation again, you can bet that we'll do this.