This is a solved dilemma. Lets take the car - There's already a huge security hole: The car key. That key disables all the security measures to stop the car f

This is a solved dilemma. Lets take the car - There's already a huge security hole: The car key. That key disables all the security measures to stop the car from moving and lets the user drive it. Why should the same key not also allow 3rd party parts to be installed, or disable any other security feature the user would like to disable? The user has already been given a device the compromises the entire security system, why do you think they need to do anything as complex as store a private key (it's embedded in the physical key). Same question for phones - The user's pin/password already removes essentially all functional security from the system. I'd add a requirement for a physical switch to be toggled in the case of the phone (a tiny toggle header, or a certain combination of presses on the available buttons should do just fine) to rule out network based access. In general though, security measures added by the manufacturer always fail, because the user has to actually use the thing at some point. So given we already have the hole, the only reasons I can come up with for continuing to forbid the owner of the device from actually owning it are 1. It adds cost to the product 2. It removes future revenue from the company (because that pesky owner might choose a cheaper repair shop if they actually own the device... however will the company maintain their monopoly on parts/service?!?!? Think of the children!)