That's part of the point rather than separate. A closed system without any way to prove it's running something often can't to get 3rd party verification or user

That's part of the point rather than separate. A closed system without any way to prove it's running something often can't to get 3rd party verification or user trust that's consistently believable. An open-source, tamper-resistant system can. Quite a bit of difference. Once verifications come in, the effects of reputation then allow users with less technical knowledge to learn what's trustworthy or not.