Finally found something [1].
> When setting your wholesale price, first multiply your cost of goods by two. This will ensure your wholesale profit margin is at least 50%.
Profit margin is the gross profit a retailer earns when an item is sold.
Apparel retail brands typically aim for a 30% to 50% wholesale profit margin, while direct-to-consumer retailers aim for a profit margin of 55% to 65%. (A margin is sometimes also referred to as “markup percentage.”)
So 50% is about normal for retail goods. Yes yes. They have physical merchandise they need to manage. Apple has engineers they need to pay to do their virtual distribution. Maybe 30% is excessive. Certainly that they're the only store and hold a monopoly on the things they allow people to do on their platform is probably fueling that margin to be higher than it should. However, if we look at Steam[2] and other console manufacturers, we see similar 30% markups. Maybe everyone is just copying Apple's lead here as "customers will swallow this". Or maybe Apple figured out a good virtual store distribution model and this is the markup needed for a sustainable thriving business.
[1] https://www.shopify.com/retail/product-pricing-for-wholesale...
[2] https://www.ign.com/articles/2019/10/07/report-steams-30-cut...