This isn't really a trust issue. People tend to take shortcuts and commit serious mistakes in the process. Humans are incredibly creative (no, LLMs are nowhere close). But for that, we need the freedom to make mistakes without serious consequences. Automation exists to take away the fatigue of trying to not commit mistakes.
I'm not against automation at all. But if all of the devs build it and get one hash and CI runs it through some gauntlet involving a bunch of third party software that I don't have any reason to trust and out pops an artifact with a different hash, then the CI has interfered with the chain of trust between myself and my user.
Maybe I've just been unlucky, but so far my experience with CI pipelines that have extra steps in them for compliance reasons is that they are full of actual security problems (like curl | bash, or like how you can poison a CircleCI cache using a branch nobody reviewed and pick up the poisoned dependency on a branch which was reviewed but didn't contain the poison).
Plus, it's a high value target with an elevated threat model. Far more likely to be attacked than each separate dev machine. Plus, a motivated user might build the software themselves out of paranoia, but they're unlikely to securely self host all the infra necessary to also run it through CI.
If we want it to be secure, the automation you're talking about needs to runnable as part of a local build with tightly controlled inputs and deterministic output, otherwise it breaks the chain of trust between user and developer by being a hop in the middle which is more about a pinky promise and less about something you can verify.
