Sometimes people are just very funny.
Imagine this. Yesterday you bought chicken meat in your usual street vendor --you know, the mighty tukang sayur--, for, say, IDR 10,000. This morning, you find out that he sells similar chicken to your neighbor for IDR 4,000. Would you be enraged and ask him to pay the difference?
You might get a bit annoyed, but unless you are insane, you wouldn't ask for compensation. Moreover, you can not blame the tukang sayur for discriminating the price. He never forces you to buy his chicken meat, doesn't he?
Sounds terribly simple? Well, tell that to these outraged Apple buyers upon finding that Steve Jobs has reduced the iPhone price by USD 200 after two months of first sale.