[Suga00]

I wouldn't say ALL of them treat people like dirt, there are always bad apples in the industry, I've come across both rude and helpful customer service agents just in the airport and from India, It's hard to understand them but they sometimes don't have all the tools/knowledge and are poorly trained. If airlines and other companies brought back call centers to the US there would still be bad attitudes, just ones we can understand better.
Airlines hire these people with their bad attitudes, I've seen people come and go very quickly because of customer complaints, but if you don't get their names and report them nothing happens.