You can be sued in any court for copyright infringement, but the US is generally unique in that punitive damages can be awarded - ie the rightsholder can be awarded more than the damage they actually suffered. In other, more reasonable jurisdictions, only actual damages are awarded. Thus it is not worthwhile to prosecute in those jurisdictions, because the damages are less than the cost of prosecution.

On top of this, I believe copyright is one of the rare exceptions in the US where legal costs of the plaintiff are paid by the losing defendent. Given that the plaintiff in copyright has so much money, they can afford to front the cost of the most expensive lawyers, further penalising their target. Other jurisdictions generally award costs to the winner by default (both ways), rather than only in specific exceptions, but they also limit those costs much more reasonably.