The fact that open source exists today is because there are charitable people out there that are contributing it for free (or effectively free). Some business models employ open source as a marketing strategy for their paid parts, which is inevitably what you really would need (and thus have the "licensing, feature matrices, or recurring billing" problem).

In the end, the pirate's product is free because they can make it free for way less effort, at the cost of the original creator of that software. While it's arguable that the piratee does not really do harm, as they wouldn't have paid for said software anyway, it is the original creator of the software that borne the cost of its creation.