From what I heard, most of said psychological tricks relay on the person you're interrogating not knowing that you're not willing to torture them.

Being able to read bodylanguage very well is also a road to information. You can use Barnum statements to give the subject the impression that you have more knowledge than you really have and then they aren't doing anything wrong if they tell you what you know already.

Depending on the prisoner. There are certainly many cases of prisoners who don't talk. If the prisoners are say religious fanatics loyal to their cause, this is certainly very hard.

In the case in the comment the example was an American soldier who probably doesn't count as religious fanatic. The person who wrote it suggested that the fast transfer of information is evidence of there being torture involved.

It was further evidence for my claim that the person who wrote the supposedly insightful comment didn't research this topic well.

I case wasn't that there certain evidence that torture doesn't work but that the person who wrote the comment isn't familiar with the subject matter and as a result the comment doesn't count as insightful.

Not reliably. This worked on about half the people.

Nothing works 100% reliably.