I can tell you that from the self-publishing perspective (I self-published my second novel - I don't know if you knew that), I receive a much greater profit. However, I believe I still receive the same "percentage". I don't know for sure, but it might just be that there is more profit, and so the writer makes more money. Just throwing it out there as an idea because let's face it - the overhead for creating a digital copy is extremely low.