The government pays for quality inspection that amounts to millions of dollars in salaries, benefits, G&A and profit by government contractors that will be inspected again at military depot installations.
Defense Contractors that purchase Military Parts for the government will require two inspection points. One inspection is performed by the contractor at their site then is bundled and shipped to the military depot and another inspection would be performed by the government to verify parts were not damaged in the shipping process. If the government required in the military depot contracts to have the parts directly shipped from the vendor directly to the depot, the government would avoid quality inspection that is duplicated and cost of that service (Salary, Benefits, General Administration and Profit). That quality service by the contractor is placed on every purchased part on the contract.