You can always count on the challenge design staff to do it for her! Remember the double-eviction veto, when Jameka claimed that she'd only been disqualified because a blue ball had fallen or bounced into her collection tube? Guess what: she was right. CBS confirmed it: the ball wound up in the tube through no fault of Jameka's. No do-overs, no callbacks, no 'sorry about that' makeup call: Jameka's out. So you have a vertical tube, balls falling from above, and you don't see that you might need to add a little flip-lid to keep the collected spheres down to what the contestants are actually putting in there -- or at least, if you're on challenge design for BB, the thought never comes up. As Entertainment Weekly's Lynette Rice basically said in her article about the event, it would hurt the credibility of the show -- if they even remotely cared about that in the first place.
On the other hand, you could make the argument that Jameka's deity of choice just decided she wasn't supposed to win that one. But still...