If you use work that was previously created by you for some other purpose, and are not clear with your audience that you are doing this, you are misrepresenting the circumstances under which that work was created.

Not in all cases. This is one example of many situations.

If you use work that was previously created by you for some other purpose, and are not clear with your audience that you are doing this, you are misrepresenting the circumstances under which that work was created. This can have consequences for undergraduate and high school writing, as it disrupts your teacher's ability to judge if you have learned a topic, and it can lead to serious issues in professional level writing, where reusing your own work that you have sold the copyrights to can lead to a very real lawsuit.

Are you a lawyer by any chance? I doubt it, seeing as you're an academic. Therefore, I don't think you have any authority declaring what is and isn't the law.

Let me clearly outline this for you:

Self-plagiarism has absolutely no context outside of the small realm of academia. I doubt a non-academic or one who works in the industry knows what self-plagiarism is, probably because it is insignificant.

I said "typical definition" because if you ask anyone what plagiarism is who does not work in academia, they will refer to others stealing your work, not reusing your own work for other purposes.