Re: I'm very curious if there is a similar Fraternities in this community
Probably most of the gang mentioned were all members of the Default trust system, or all of them ? They were like members of Mafia they have the power and in control. They have the authority to red trust anyone, because some of them were abusive with their duty.
Not all, it depends on the gang you refers... take a look of Polar91 gang there's no any single DT of the members 
DT members aren't a Mafia or something criminal, it can defined as a trustworthy person in this forum. Of course they could give green/neutral/red trust to anyone, but it must have an evidence or a reason why they give it. If they were abusive or misusing the power they could get excluded from DT.