At the end of the day, you have to remember that Apple devices are essentially a sealed unit. Any claims they make about privacy cannot be proven - they could slip tracking and keyloggers into every device, and unless you build a device from scratch and program it yourself, there’s nothing you can do about it. You have to trust that they won’t do that, and Apple is in a relatively unique position (particularly compared to google and facebook) in that the business isn’t designed to profit from this, so they have no real reason to do so.