It's meant to convey a degree of respect while maintaining social distance, i.e. not wanting to appear overly familiar.

It's a very common part of the social dynamic in the southern states and intended as a positive gesture.

Particularly useful in places like Louisiana where pronouncing Cajun/French derivative last names if you're not native to the area leads to butchering pronunciation. Which, ironic given your post, is pretty disrespectful.

Or head on up north to somewhere like Chicago or Milwaukee and see how you do with a last name like Pryzbilski...