I think the problem is that there are too many suppliers. Everyone wants to be a middle-man. If the government asks for domestic parts from it's big contractors, the big ones ask their small ones, and they ask theirs and so on. But at the end of the day someone realizes it's cheaper to outsource it - does so - and forges the documentation. As the part travels all the way back up the chain each one says it's domestic.

The chain is only as strong as its weakest link.