If I jump the fence or sneak into a theater, I take the place of a paying customer. I am stealing the ability to sell the seat, so they are in fact denied the resource. If I copy a song, the original owner still has everything he started with (time, stuff, etc).

Also: I never said it was a strictly western notion. I don't know enough about other cultures to make claims. So I qualified my statement to those places where I know it is correct. I appologize for offending you by not making overly broad statements.