I am guessing the 30% quoted is specifically for digital goods because 10-15% is the fair price for connecting buyers with sellers of physical goods. At least that is the case with platforms like eBay, Walmart, and Amazon.

Maybe someone can explain how the selling/labor costs of digital goods are twice that physical goods and justify 2-3x the commission. I would like to hear it because I am admittedly ignorant when it comes to the costs of content delivery - all I know is that egress can get expensive.