Upper Management doesn't want people to "violate" the FARs, but they do want people who will work within' the Grey Area to interpret them and accomplish the task of going from point A to point B.

"Duty time starts when your phone rings." -Local FSDO

But it doesn't really matter, imagine the guys that get an 8PM to 8AM shift of being on call. Are they sleeping all day long to be ready for the "potential" trip that they might get that night? Or are they up all after noon doing normal everyday chores and whatnot? End result is the same and generally these guys are just as tired as the day shift would have been.