On Reddit, it's just a community having a discussion. The participants, even the moderators, are mainly involved in guiding a discussion, and Reddit just facilitates that.
On Stack Overflow, the moderators really are working directly on improving the site's content. They're practically unpaid editors.
So do non-moderators. In fact, there are some users who do more work towards improving the site’s content (via editing, handling suggestions, etc.) than some moderators. In fact, “trusted users” have access to many of the same moderation tools as moderators, and editing content is actively encouraged (via functionality, badges …) for all users.
I'm not saying that there isn't a "common-sense" counter-argument to some of the cases I noted, but "common-sense" is a defense to be raised in court, the case is brought based on if the law could apply. In my mind that's troubling as it weaponizes the law in a way it could easily be abused.