[hnarn]

>So where does the company get the authority to license it?

The company doesn't need any authority because anyone can "license" public domain software, just like I can sell you a star in the sky. It's a worthless piece of paper, its a gimmick and a way of making a donation to a cause you appreciate.

>Couldn't the person who put in into public domain go to the country and sue them saying the company is licensing their code?

Again, you're misunderstanding what public domain means. "The person" you mention has no right to sue anyone because the thing being discussed has been released into the public domain. Nobody owns it.

To illustrate: when you say (paraphrased); "The author could sue you for misusing what he/she put in the public domain" the logic doesn't hold, because if the author could to that it wouldn't be released into the public domain.