Devices with proprietary OSes spend more and more time phoning home, then exchanging data officially for "updates". They probably tell the truth, but should one

Devices with proprietary OSes spend more and more time phoning home, then exchanging data officially for "updates". They probably tell the truth, but should one of them decide to hide users data exfiltration or other monitoring practices behind those updates, it would be quite hard to catch them. In other words we have no way to tell that they're not already doing this.