Whenever one spends there money with an institution it does not mean the customer has the right to disrespect the individuals humanity. Being a customer service agent of any kind doesn't mean that you are a slave to the customer.
The problem lies with the Audacious Consumer who believes they deserve (something)--and with the institution that comply with the childish behavior of said consumer.
I think that Americans have separated their interaction into two different categories (among other things of course): Business and Personal.
Business Relationships are completely sold out to the dollars. American Consumers believe that they are entitled to be treated as a Lords of sorts because they have the money that the business wants; and that on the terms of Business they can disrespect their salesman without being held accountable for their behavior during their transaction.
I've worked in many different positions of customer service, and I have dealt with so many people that believe they are "due something" --especially in the food industry--even whenever the profit margin doesn't reflect or compensate for any customer service--as if respect was quantifiable.
The truth is that regardless of a business transaction or a personal exchange, we are called to treat people with respect.
We are all guilty.