Trusted computing is similar, too. It's a huge win for the user in terms of security, as long as the user owns the master key and can upload their own signatures. If not, then it suddenly becomes a very powerful form of control.

The more fundamental issue is the distinction between "user" and "owner" of a computer - or its component, or a piece of software - as they're often not the same people. Security technologies assert and enforce control of the owner; whether that ends up empowering or abusive depends on who the owners are, and why.

Often? Only really in the case of a corporate computer. But Android locks these things down for everyone. In fact corporate owners can do things normal users can't.

For example I've heard (not confirmed) that with a Knox license you can add root CAs on Samsung. I don't think it's still possible with other MDMs or other vendors.

On the contrary, that's the more common case. It's the case with any computer at work (unless you're IT dept), in any work - there's hardly a job now that doesn't have one interacting with computers in some form or fashion, and those computers are very much not employee-owned. Same is the case in school setting, and so on. About the only time you can expect to own a computer is when you bought it yourself, with your own cash. The problem is, even when you do, everything is set up these days to deny you your ownership rights.