And a public figure is just a person that reporters take an interest in.

There is a difference between a merely famous person (eg Kim Kardashian) and a public figure like an elected official, in whose good behavior the public has an interest (as distinct from being interested in it in the colloquial sense). I mean this in the sense of the word republic which is a contraction of the Latin res publica or 'public matter.' This is why private individuals enjoy a right of publicity to their own likeness and copyright protection for their public performances, but the identity and doings of legislators and government officials (within the scope of their official activities) are in the public domain.