Because the evidence is technical and often has to be created. The government charges appear in the USCIS fee schedule, Form G-1055, while the real spend goes on documenting proprietary knowledge, reviewing the customer contract, translating French records, and answering the request for evidence that this category attracts more often than most.
Price the second round, because there usually is one
Two costs dominate and neither is a fee. The first is documentation: pulling internal material together, having a technical person explain in writing why the knowledge is the company's, and getting confidentiality and training records into a form a stranger can follow. The second is legal review of the commercial arrangement, which for an offsite placement is not optional.
Premium processing shortens the wait at a published cost and does nothing for the strength of the file. Hypothetical example: a grain-storage sensor manufacturer pays for premium processing to hit an installation deadline, receives a request for evidence within days, and finds that the fast decision it bought is simply a fast demand for the documents it had not prepared, with the deadline gone either way. Where the customer contract itself needs redrafting, that legal work sits on the commercial side of the business rather than in the immigration budget, and it is almost never quoted at the outset.