I find it intriguing how people keep making these mistakes. Something is not 'public' because it is shared by many people and used as if it is public. It is a wolf in sheep's clothes and it isn't even lying about it.

Github, Facebook, Twitter, Youtube, Sourceforge, HN, Slashdot... These free services are not public. You might treat them as such, but you are foolish believing they are.

If you cannot see the difference, I suggest to read the excellent Wikipedia article. [1]

[1] https://en.wikipedia.org/wiki/Public_service