As someone who has lived in the North (Ohio) in the South (North Carolina) and the Non South (Florida).

I doubt the deer do anything faster..the reactions of the people are just slower. If there is a correlation of deer anxiety it may be due in part to the constant hunting with dogs..that puts the deer more on edge. First instinct at sound is flight! First movement to run, is to load up the legs for quick departure=ducking.

Disclaimer: People in the South are great and outwardly friendly..this is no slam on them, they are just more laid back.

And I'm not saying "you" hunt with dogs, but it is the primary method used in the areas "I" was in, in both (Fl. and N.C.)