I’m not entirely sure if you understand what fiduciary duty actually means if you read federal ethics laws and don’t make the connection. Just because you can’t control+f “fiduciary duty” doesn’t mean the concept isn’t identical. Hell, there’s literally a law that bans insider trading futures on unknown information. Not “kind of like it”, literally named verbatim.
And I’m not putting words in your mouth, I’m just calling out your revealed preferences.
You're simply not using the word 'fiduciary' correctly. You seem to have expanded it to mean any sort of legal or ethical obligation with respect to markets, and that's not what it means.