So it's rare, but if there's a piece of bread stuck in the bottle cap that's outright Chometz. Are you going to start telling me it isn't a problem because the bottle is upright?
Do they have a mashgiach temidi at the production of the caps, or are all caps inspected by the mashgiach?
Bottom line, the need for a mashgiach temidi at KFP soda bottling is almost like the need for DW to have kids clean the nooks and crannies of furniture with toothbrushes and q-tips (after they have been thoroughly cleaned by conventional means). However, both make people happy and keep people busy. Some people are happy to see the mashgiach (and it keeps him busy), and others feel the need to know that the furniture was cleaned with a toothbrush and q-tip (which keeps the kids busy).
ETA: unless it's done in a plant like
this which I doubt.