Maybe because you see the secrets of the universe and all I see in your hand is a gum wrapper. You define natural-born citizen the way you want it to be and expect people to accept it. Well sorry to disappoint.
I define "natural" in the only manner that it is possible for a rational human being to define it.
"Not requiring the intervention of man."
Words mean things.
I would tell you to look up the etymology of words such as "Nature, Native, Natal, National, Natural, etc but given what I perceive to be your level of intellect, I don't think you would know how.
Suffice it to say you can learn a lot about the correct meaning of a word by exploring from whence it came.