You've asked a lot of questions here. I shall try and answer.
Firstly, you need people around, who as I said before, are loving, trustworthy and fair (FLT). There is another thread at the moment about an abusive son aged 21. He's grown up in a house where he had an abusive father (towards the mother at least), this is a different situation. OP here hasn't said there is abuse.
If you do not have a situation where the people around are loving, trustworthy and fair, then the people who are have to create one. Usually that is by leaving a relationship or cutting off family members. This answers your question about "what if an adult is wrong?". An FLT adult will listen to opposing viewpoints and consider that they may need to adjust their assessment accordingly.
There is a difference between raising your points for this type of consideration, and arguing. Arguing starts where it becomes not about giving new information, but debating values. For instance, my son wanted to attend something that he could theoretically get to without disrupting other commitments, but my issue was actually that he will be too fatigued from the first to perform well at the second, which is more important in my opinion.
On this matter, his opinion is not as informed as mine, because he is quite a young child and doesn't have the long term vision to truly prioritise accordingly. I would be fine with him pointing out that actually we do have enough time to get to both things, and even some pushback on what is more important, but after exchanging views, I'd expect him to accept my decision with as much grace as he can muster. This exchange of views is where he learns how to present his ideas and essentially "debate".
The FLT adult may still be wrong though. They may make a decision that with hindsight (because they are an FLT adult), they saw was the wrong one. They address that by being honest and apologising. That is a very valuable lesson for the child: you can be FLT and have great intentions, and still be wrong - and you still have to be accountable even though it was unintentional.
That's a complex lesson about trust. The people in your life who love you most will sometimes make mistakes, particularly at times where they can only choose one road and can't switch later on down the line. Seeing those in authority admit that and learn from it is very important for development. Again, it goes back to being an FLT adult.
I don't think we want a world where we are saying children should routinely test and challenge the worthiness of their parents as authority figures. I would like a world where adults sufficiently protect all children so they don't have to take that approach with people like their parents and their teachers because they are all FLT adults (or they aren't allowed to teach/parent).