Rule about balls

[BrianR]

<G13> Balls Contained in ROBOTs at the Start of a match - Each ALLIANCE will start a match with 40 balls.
Each ROBOT may contain up to 10 balls at the start of a match. Any balls not contained within the robot
will be evenly distributed between the alliance ball corrals. All of the balls must be contained within the
ROBOT’s 28” x 38” x 60” starting volume and must be clearly visible from outside the ROBOT. The
Head Referee will require that balls outside of the starting volume be removed. It is the responsibility of
the head referee to verify that this rule is satisfied prior to the start of the match.

So do they have to be totally visible, from all angles, which sounds a bit unreasonable, or should the referee just be able to see each ball from some point outside of the robot, and if that is so, what happens if because a bunch of balls are stacked together, a ball is hidden by other balls, and is thus not visible to the referee? Is there a penalty for that, I can't find a penalty for failing to comply with this rule, so what exactly would they do in that situation.

[GDC]

All balls in the robot must be visible such that the referee can easily determine the number of balls. The match will not be started until the Referee can verify the number of balls in each robot.

If a ball can be hidden, then the design is not adequate and needs to be improved.