I don't know what kind of QC they do at BH so I can't speak to that. That said, there are a lot of small parts and I would suspect that sometimes the missing parts actually were packed but were lost upon unpacking. I'm not saying that is what happened in this case, but I imagine it happens more often than one might expect.
Plus, the internet is a great place to vent so we probably hear about EVERY missing part, but we don't hear about every perfect order that makes it. I have a feeling the problem seems bigger than it actually is from our perspective.
That said, it does happen - My kit was missing the BH badge. They quickly shipped me one, but they did incur the extra shipping costs just like they will in the case of the resistors above. That gets expensive quick and it would be in BH's favor to be more accurate (plus it is disappointing as you have pointed out).