David Foster Wallace's take on this was that my own reality is so overpoweringly real, that it's hard to see you (or anyone else) as real.
everything in my own immediate experience supports my deep belief that I am the absolute centre of the universe, the realest, most vivid and important person in existence. We rarely talk about this sort of natural, basic self-centredness, because it's so socially repulsive.... Other people's thoughts and feelings have to be communicated to you somehow, but your own are so immediate, urgent, real....
The remedy he proposed:
[Instead:] if you're aware enough to give yourself a choice, you can choose to look differently at this fat, dead-eyed, over-made-up lady who just screamed at her little child in the checkout line - maybe she's not usually like this; maybe she's been up three straight nights holding the hand of her husband who's dying of bone cancer, or maybe this very lady is the low-wage clerk at the Motor Vehicles Dept who just yesterday helped your spouse resolve a nightmarish red-tape problem through some small act of bureaucratic kindness. Of course, none of this is likely, but it's also not impossible - it just depends on what you want to consider.
http://m.guardian.co.uk/books/2008/sep/20/fiction?cat=books&...
What works for me sometimes in dealing with customer-service folk is to ask them what they would do in my position.