Just bad luck. As with any store or support paradigm, there are people whose personalities are more ideally suited -- and even then a person can be having a bad day and misinterpret what a customer needs or wants, or dealt with so many other issues that she decided that your inquiry was lumped into the same unsavory category as previous callers (when it wasn't).
Psychology - it's more convoluted than tax laws.
Especially as I recently had to call a company, which also employed people from southern states, and had utterly no problems with assistance or attitude, and I'll admit I can be persnickety at times. And having been in the field and trying to help others, it's not as easy as one would believe it to be. Nor is it/should it be about reading off a script, or saying "We don't cover advanced issues", since problems can come from numerous avenues and pre-purchase help and post-purchase support are going to do a heck of a lot more to show how much a company truly gives a rat about customers to begin with. If you were paid slave wages, how polite would you remain for how long? No, it's not about "If you don't like it, leave" since most people who say that have never gotten to have to live it...