I would tend to agree, but have no proof in saying so. How do we know that the stock filter is better than the Fram? Just because it is stock doesn't mean that it is better. There are lots of examples where stock is not better. Brake pads quickly come to mind. A stock part is chosen for its cost/performance ratio, and in some cases, cost is the only concern.

With a part like an oil filter, one would assume that to ensure the least amount of warranty claim liability, they would use the best filter possible. I wouldn't necessarily bet on it, though.

It is an interesting question.