I know its easy to blame the manufacturers but I don't believe they are entirely at fault here. Its not so much the size alone but that in these facilities they are not being cleaned after every run. Certainly the products that spoil are getting sanitize appropriately (eggs, dairy etc) but uncooked grains I suspect have a much larger time line for cleaning.
Lot of these things are dry ingredients. So they do not even need same level of standards as anything wet. They keep well enough and earlier in manufacturing chain things are much worse. Just think all of the places your average wheat grain go trough from field to finally being baked... Many parts do not have the strictest standards of steam cleaned stainless steel...
