I don't think we do; there's a difference between "trustworthy" and "capable of doing no wrong". If I don't trust someone in that situation, it's not necessarily because I don't trust them in general, it's because poisoning the well makes ANY decision they make dubious. Them getting the information ahead of time just sets the whole situation up for failure.
I don't think you understand the situation fully. You say things like "if I had already decided which one to pick" but you never had the opportunity to pick because you weren't told the options because you rolled before you could be told. Your stated default response of allowing the DM to pick is a healthy attitude, but not all players are you, so allowing pre-rolling is just setting up for the time where someone throws a fit because the DM picked for them. Maybe you run with players where this will never happen. That's fine, but not the case for everyone.
I mean, you can't just always assume total competence; before we even start playing, should we just assume the characters did everything right, end of story, pack up and call it a day?
This would be a nice "I think we understand each other well enough, let's end here" moment if you had simply written that in a manner other than that of a reluctant apology that a child only gives because his parents made him.
First part... trustworthy means "worthy of your trust". If as you say you will not trust them to make these decisions **you** are declaring them "untrustworthy" - maybe you feel everybody is untrustworthy but then again maybe not. But if you look at the second part which you separated from this, even you recognize there can be a "healthy response" by which i assume you would consider "trustworthy" as in you would trust me doing that. So, doesn't that example make your claim that "poisoning the well makes any decision dubious" actually a dubious claim?
Also, no, i did not misunderstand. i gave two cases - one was "if i had decided" the other was "if i had not decided" and gave a complete answer.
And i am sorry but... anybody who believes rules are what causes fits to be thrown or that rules can prevent fits from being thron at their table has a very flawed idea of what causes fits and other such outlandish behavior in social situations. I don't write rules or use rules to "prevent fits".
Also, i have never claimed this approach was good for everyone, i even acknowdlegd several times. But just as clearly, it is fine for some. If you look back on this thread and others, there seems to be no shortage of "pre-rolling is bad" or "pre-rolling leads to" with much broader kinds of scope than I have tended to use for when pre-rolling is fine.
As for your "total competence.. call it a day" nonsense, thats not what was being referenced - hence my not saying "total competence" at all!! - you should maybe look at that blog the Op referenced (not my first rec tho) or go google things like presume competence" and such as it applies to RPG. it refers to a trust state between Gm and players where the Gm treats scenes and events and general play habits as if the **characters** are acting at their general level of competence without the players needing to state every second of every turn of every scene in exceutiating detail to prevent a thumping from beyond.
EXAMPLE: "you did not say you looked up so the macguffin gets surprise". vs "on getting to the door, you see in and... the first thing that catches you eyes are the macguffins up on the ceiling. You almost missed them but..." when a parties passive per would spot the threat OR when a deliberate check to "look into the roll" rolls high enough even without the "i look up" safe words.
it has nothing to do at all with your totally imagined case of the characters win without the players so call it a day crap.
Finally, there was no attempt at apology in that last comment. if you read into it such, you were in error.
Rules will not solve trust issues. They will just shift where that underlying trust breakdown manifests.
Rules will not prevent inappropriate behavior like fits.
Most games, like most relationships which a game is, are better served by solving the underlying trust issues or behavioral problems than by patching more and more "restrictions."
Your cheating spouse wont be "more faithful" or you "less suspicious of them" because you install a tracker on their phone and take away their inner-city apartment - any more than you being dubious about a player's ability to make "reasonable choices" will be solved by not allowing "pre-rolling." that same "worry" about his "poisoned well thoughts" is gonna be there when he sees scenes with other characters that his is not at and later a choice comes up where "are you really sure his decision wasn't poisoned by tat out of character knowledge?" and a million other cases.
If you resolve the trust issue to a point where you and them are fine with each other and that decision making, those issues can be non-problems with an occasional ooops and not an underlying sense of "suspicion."
Deal with player-to-player trust in player-to-player not in game mechanics.