According to the article, they launched this audit and have already pressed the issue to the point that the three factories in question are no longer employing

According to the article, they launched this audit and have already pressed the issue to the point that the three factories in question are no longer employing 15 year-olds. Apple enjoys high margins because of a very effective marketing strategy, excellent product design, and an extremely loyal customer base. It has nothing to do with the fact that their subcontractors were employing a few underage workers.