Yeah, I think most people end up learning the hard way that there's no equivalent to "attorney client privilege" in regards to coworkers and managers.
I like all my current coworkers, I think they're nice and smart people, and I don't think they're assholes at all, but I don't really say anything to them that I wouldn't be fine with HR hearing about, even during off hours. They're not bad people, and I don't think that they'd be overly vindictive, but I've been burned enough by coworkers that I have trouble trusting them.
Personally it's pretty hard to get me to tattle on people [1], in no small part because I think that most people don't need to be reminded six times for one mistake. I also just think that unfeeling bureaucracies are capable of unspeakable evil but that's far more of a tangent that I'm not going to get to in this message.
[1] With obvious exceptions, if I were to see outright abuse or fraud or something then I'd probably tell someone.
