I see, but this is unfortunately the rational behavior in many cases, as being nice will get you a sorry and a goodbye.

I have worked in places where customers expected some kind of service provided and the nastier behavior got rewarded the most.

While for some this behavior come naturally, I think there is also an element of conditioning to this behavior.

Also, people are not calling because evertyhing is great. Some level of frustration and anger must be expected in such a job. But my impressions is most companies don't train their workers to handle such scenarios.