I've not vs. I haven't

[Acadiafall]

I don't get it. Im a Limey and I have never said, nor do I know anyone who has ever said "I've not"

 

[BEACHBUM]

In any case you cain't say hain't if you tain't from the South.

 

[Flatspotter]

In any case you cain't say hain't if you tain't from the South.

Let's leave my taint out of this.