Yes, many product segments have non-transferrable warranties. NVIDIA warranties are non-transferrable, as are Herman Miller warranties. That being said, you can

Yes, many product segments have non-transferrable warranties. NVIDIA warranties are non-transferrable, as are Herman Miller warranties. That being said, you can have the original purchaser make the claim for you or you can pose as the original purchaser/doctor the receipts, but it creates a big hurdle for secondary markets. I don't understand what you mean by iCloud/Knox lock. As far as iCloud lock is concerned, it is only for stolen devices in which the owner did not deactivate their own icloud account. Where are your sources for gray market of company workers defeating the lock? I'd imagine if an Apple activation lock is bypassed it would have to do with resetting the password on the iCloud account.