As I'm usually Uncle Heavy, and seem to attract my fair share of complaints about how I operate, I'll just make it clear here: I publically post as a moderator in a thread to indicate that the thread is in my opinion salvageable, but that more than one poster has either come dangerously close to the line or crossed it entirely. It's up to the people in the thread to get it back on track. In general, I try to indicate where and how it's gone off the rails so that people can adjust their behavior accordingly.
When I publically chastise or ban someone, it's an easy way to say "that behavior? Don't be like that." so that everyone can see where the line is and have an object example of what crosses it.
Finally, though, as users of the board, you're just going to have to accept that you won't see the whole story. Very often, what you see is the culmination of a series of actions, starting with gentle correction and ramping up through more aggressive warnings, temp bannings, and finally the Hammer of God. Ask any of the new moderators what it was like having their eyes opened to the behind-the-scenes action that comes with being a moderator, and they can tell you: it's night-and-day. No banning happens in a vacuum, and there's always a back story. Very often, revealing that backstory would be completely counterproductive. In other words, you see a small part of the situation, and that's by choice on the moderators' parts.
That is not going to change.
I think I have about as good a perspective on the moderation here as anyone but Iago, because I was the first assistant moderator drafted back when McAnally's was a mailing list. Moderation here has never and will never be random, whimsical, or prompted by personal grudges on the parts of the moderators. We simply do not operate that way, and any perception of personal bias is, in my considered opinion, a phantom of the imagination.