My personal guess about it is that it is that most people attribute to animals a lot more agency than they really have, and the story is written with an authorial worldview that assumes that most people’s views on this matter are actually true. Given that worldview, no explanation is needed at all. Of course, that worldview is itself inconsistent, but the inconsistencies have relatively little relevance to talking to snakes.
My personal guess about it is that it is that most people attribute to animals a lot more agency than they really have, and the story is written with an authorial worldview that assumes that most people’s views on this matter are actually true. Given that worldview, no explanation is needed at all. Of course, that worldview is itself inconsistent, but the inconsistencies have relatively little relevance to talking to snakes.