I wish this was more like a traditional wholesaler/retailer relationship.
TL;DR: a thought-experiment… could authors set their subs fee (as now), and multiple retail outlets always feed that fee in full back to the author, and add whatever they like on top for keeps, and take their chances in the market?
So…
As a wholesaler, we authors bring our goods/services to the mass market and set a trade price. Substack is a retailer (and platform of course), and it adds just over 10% to my trade-price as its cut (and a little more to account for its choice of Stripe as a checkout partner). Apple is also a retailer platform, and chooses to add just over 30% as its mark-up. Either way, the buyer can shop-around for the best deal, and the wholesaler (me) does not care as long as the flow of funds works. People will see different prices, but hopefully they’ll get the point that they’re in a posher shop (with maybe more trusted commerce, better customer service, whatever).
People here who say “Apple is not adding anything” are not quite right: they add a retail path (and a VERY wide-reaching one). This is (in my simple mind) the same as a shoe shop adding its mark-up to Nike trainers – which is probably waaaaay more than 30% by the way. Nike does not care, they get the wholesale price anyway. (And yes, I know they cut special deals, but the principle stands.)
The value the retailer adds is always (i) a path to market, plus (ii) customer service. These have real value.
(Nerdy maths point on that “just over 10%” etc.: Substack levies 10% of a £100 sub, so gets £10 and I get £90. But if I set my “wholesale” sub at £90 then that “retailer’s cut” of £10 going to Substack would be 11.11% of my £90.)