In a lot of situations, like #15 at Mississippi, you do not see the ball cross the hazard line and as the rough is deep enough to lose a ball in you cannot just asume that it's in the hazard. As the situation at the top of this thread said the ball was found later outside the hazard and just because everyone said "well it must be in the hazard", to me, it isn't known that it is in it. I hit a couple of shots today and without certainty I knew they were in the hazard and there was no way I was looking anywhere else as the possibility of finding my ball outside of the hazard was 0% and I wasn't going to waste 5 minutes looking anywhere else.