Actually, it is because US companies don't rule the world and really don't have the power to stop international pirates. Plus, you actually have to have evidence before ou arrest somebody and it is hard to get a warrant so you can collect evidence overseas. If you get evidence without reasoning of getting evidence(like getting lucky and knocking on the right door), you can't really use that evidence. The only place companies could stop them is if they press them in the US(not likely) and are exporting them. They can get them as they try to export them. So you see, it is really quite complex for a US company to prevent piracy overseas and I'm sure Interpol is going to waste their precious time arresting a local Mob boss. They have bigger fish to fry then pirates.