After reading some meta questions, it seems there are a lot of unanswered questions, and also that it's not necessarily a problem. I'd still want to know on what criteria I should accept an answer.
On the questions I posted (except one, that was actually even harder to accept) I never had more than 2 or 3 answers. From there two possibilities:
The answers go in the same general direction, with a few slight nuances. None of them explain much better than the other, or have significantly more votes. Which one do I accept?
The answers go in different directions, contradicting each other. None of them get more than 1-2 votes, I have no expertise to know who is correct (that's why I'm asking in the first place). Which one do I accept?
If I wait for more answers, by experience nobody answers, there are a lot of questions and when you see 2 answers you're not likely to go give another one, even less if you see both answers are basically saying what you would have said. And maybe the correct answer is already there, but I can't tell.