When we moved down to NC over 10 yrs ago (has it been that long?) we were forwarned about that tendency. Of course, the other side of that are the ones that have the turn signal on and don't mean it.
You'll find plenty of the other too, unfortunately.
Even worse are the ones who don't know what a Yield sign is. My mom was nearly killed 30 years ago by a dumbass who blew by a Yield sign and cut right in front of her car so close that the front corner of Mom's 1973 Lincoln Continental hit the ass end and pushed the car about 40 feet.
Lucky for my mom there were witnesses who told what happened to the officer at the scene and the SOB had a no limits policy.