I think some of it is that people are more likely to report a post by someone who isn't as popular. And Mods do seem to respond faster if they've gotten multiple reports of an issue (I'm thinking of one in particular that set a record). So, a new, or unpopular poster (either because they tend to be in the minority opinion or because they tend to express themselves in a way that rubs others the wrong way) may be reported many many times, where a popular and well known poster would only get one report for the same type of comment. The mods then react to that by going to where the reports are.
The mods have commented on why they delete posts instead of editing them. They can still see the deleted posts, but if they edit them, then they can't see the original post. This allows them to see a pattern.
I do agree that I wish the mods would post a note when they've taken action. It would help up the transparency and reveal more about what's going on.
I'll also say that if you've had something deleted or edited or something, I don't see the harm in asking. I had a topic moved and asked why. I got a response, and decided I was fine with the decision. If mods are refusing to answer why an action was taken when asked, that seems like a bigger problem. I've not experienced it, but if others have, I would want to know about it.
I'm sure I, and everyone else on here, has occasionally worded something badly and been offensive. I would hope that if people have problems with me, they would let me know directly, especially if it's a general style of posting. I know I'm on here in part to avoid offending people. I think in general, dealing with things in PM is ideal.