For sarcasm that one would reasonably expect almost anyone to notice, I still think it’s group-membership related, but the group is something very broad, like ‘society’.
It can be a way of saying “We’re in the same boat together.”, floating in a sea that may or may not be populated by an out-group.
It can be a way of saying “We’re in the same boat together.”, floating in a sea that may or may not be populated by an out-group.