I'd posit because the the product in the case of pirated or black-market software is almost always clearly inferior to the original software-- it has been cracked and changed in various undefined and poorly understood ways (certainly to the average person). There is some chance the pirated software will give you a virus, or be fake, etc. There is uncertainty about the product and people are naturally uneasy about it.<p>I suspect a similar reason for why most people don't buy black market goods: pirated handbags or knock-off electronics brands, for example. The quality is perceived as worse, or at least unknown.<p>Digital media (movies, music) on the other hand are more widely understood to be "exact" copies of the original and so there is less concern about the quality of the illegitimate good, to the point that it isn't considered illegitimate.