No, what insulates them from fiduciary responsibility is the fact that there is no fiduciary responsibility to shareholders. I’ll say that again: members and/or managers of an LLC, and officers and directors of a corporation owe no fiduciary responsibility to the shareholders to make them money. The fiduciary duties owed under US law are as follows: 1) the duty to be informed; 2) the duty not to usurp corporate opportunities.

As far as I can tell the fiduciary duty to make money for the shareholders is something that Jack Welsh of GE said enough times that people remembered it. However, I’m always interested in additional details concerning the history of this meme, and happy to learn more.