Piracy is a reality in app stores. But you don't see developers running around to sue people downloading pirated copies. That's because they acknowledged that these people won't pay them and focus their efforts on people who do pay them. Most of the apps even have free versions just so that users can sample they app and judge it for them selves before buying it. All these are adaptations to the environment in which they operate. Content industry on the other hand refuses to adapt.