I work at a big-box retailer. All the time we get recalls of product, because it's not legal for us to sell. Usually, these are recalls of mislabeled food or clothing but once or twice I've seen recalls due to copyright violations.
Any item sold in violation of the GPL is going to be the exact same thing. The FSF has explicitly said that that's what they want to happen, that they're not going to try and sue Best Buy or Wal-Mart over an accident.
Apple distributes the code. That's simple English. Apple, Wal-Mart or Best Buy can't sell illegal copies; that's the law. No one is interested in fighting a major company in court over an innocent mistake, and the FSF has shown by its actions its willingness to avoid court, so all of these companies are going to make the illegal code not available to the consumer and that's going to be the end of it.