Aside from Apple’s strong stance and history of protecting the privacy of users, we also have security researchers MITM’ing the traffic sent from iOS devices to Apple, and every jailbreak gives an opportunity to look deeper; if they were acting badly, someone would find that out soon enough.
If some surveillance happy government bans some VPN software then Apple is going to enforce that ban much more thoroughly than Google or Microsoft ever could.
Every time I see a comment about an open source phone I am curious if the poster of the comment is actually going to fine comb the code base.
If you paid someone (even multiple people/companies) to do professional audit over OpenSSL, it would be prevented.
Now, with closed software you are lost and the only thing you have is a TRUST the SW developer. Because inspecting blbs is much more difficult. And I don't trust them.