I can give you an example. The best manufacturer of electronic circuits for electric guitar pickups works by himself from his home. He has two or three subcontractors who make components for him and 90% of his products are sold in the United States. That is what exporting is for him.
Next door, you might find, say, a manufacturer of roofing beams for farm buildings. He has 200 employees, but he sells only in the local market.
If the government has no data that can identify each kind of company and the markets each is producing for, it seems like a game of blind man’s buff.