So how do you know someone is who they say they are? If someone is born and never acquires a nationally issued ID, how can they even prove they are american and have the right to be there?
If your birth was never registered? That can be a problem. https://www.wnycstudios.org/story/invisible-girl/
And I imagine if, as an adult, you don't have a birth certificate, aren't sure where you were born, and don't know your social security number, things can start to be difficult.