"Why do you think people don't use amazon?"
They do, actually. Their MP3 store launched a year and a half ago and sell about 10% of what iTunes does. Some estimates place them as the #2 digital retailer:
Furthermore, that figure almost certainly represents sales mostly taken from iTunes. Almost every iPod/iTunes user I know has switched.
It's worth noting that Amazon also refuses to sell me music simply because I do not live in the US. I fail to see how this is any better than iTunes Music Store. At least with iTunes I have the option of using gift codes to pretend I live in the US and get my music that way. With Amazon I have no such recourse, as far as I have been able to find out. It's credit card or nothing. (Paypal knows where you live too so that doesn't work either.)