Lots of packages, from lots of sources, handled multiple times --- a difficult chain to keep intact and secure. Add to this our natural impulse to assume that if something is already packed, then it must be okay. This could be a recipe for disaster. However, a well run ship with a well trained crew view it differently. They see ship's stores as simply one more element to add to their list of searches and inspections; one more way to insure safety of the ship, it's crew and cargo.