The scenario where they're lying would would mean they're falsely responding to countless subpoenas for data by claiming they don't have information that they do. This would be a massive globe-spanning crime requiring the coordination ("conspiracy" in criminal law) of hundreds or thousands of people, and also enormous civil liability. This would instantly wipe hundreds of billions of dollars off the stock and destroy their reputation, all so they could ... what? It's cheaper and easier for them to simply collect less data in the first place. Useless user data is nothing more than a liability for Apple.