Well in the US I believe when situations like piracy happen and they affect corporations, it's up to the 'victims' to take legal action against the people pirating stuff. If the music/movie/whatever industries never paid attention, the government wouldn't take any action.
Yeah, this is true, but you can only take legal actions against people who have been caught. If I create a website where people can download movies illegally, nobody knows who I am, so how can I be prosecuted? The corporation can't even do anything about the website on its own unless it goes to the authorities, and the site can be taken down. When that happens, the owner or creator of the website will just create another one, and the price continues.
It's only the government that has the authority, jurisdiction and resources to fight it. A movie industry in the US cannot act against a piracy organisation in Asia, Europe or Africa.