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Legally - prohibit selling physical goods that contain digital locks unless the owner is given a key. Period.
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That's all you have to do. If I own the device, I get the keys for the physical locks, and the keys for the digital locks.
I'm completely ok with manufacturers locking down computers for security, in much the same way that I appreciate that cars have door/ignition locks.
But if I own it - I get all the keys. I may never use them, but they are mine, as part of ownership.