It's due to competition (or lack of).
WSB is by far the biggest dog in the Atlanta talk market. And, it's signal is strong over most of North Georgia (actually, I've gotten it all the way in Anniston, Alabama during the daytime).
Their competitor's signals fade once you get outside of Atlanta proper.
On the other hand, I imagine the NY talk stations have more competition from other talk outlets.
All of Georgia doesn't have two-thirds of the NYC Metro population. WABC has enormous range. I remember getting it in Indiana in the daytime when I was a kid. (Traveling with my father and hoping to listen to Mets baseball then.)
ML/NJ