This is a major misunderstanding by the Military, the Government, and Americans in general regarding Afghan society: Money is no exchange for lost relatives.
In Afghanistan, families are much closer, and they stay together in the same village for the entirety of their lives barring some terrible event. But in America, families are much more loosely knit.
Also, in America, money is much more important in our culture than it is in Afghanistan. We file civil suits after murders while Afghans live a much more simple life with less importance put on monetary gains in exchange for lives lost.
I was afraid to hear on a recent episode of Frontline that the caricature of American soldiers in Afghanistan is they come and kill your family to only return with freshly pressed money to rectify the situation.