[JaggedJax]

The 20% take is not per sale. It is per whatever your monthly charge is for selling your app.

For example, if I make an app that manages your product data on Shopify and BigCommerce for $100 per month. Shopify forces me to pay them $20, and BigCommerce forces me to pay them $20. I am only making $60 now.

If I want to support 6 platforms that have this pricing model, I now have to pay them a combined 120% of whatever I charge for my app!? Workarounds to this are using private apps so that to Shopify it looks like the Shopify Storefront owner built their own custom integration, or potentially breaking your software into a bunch of tiny separately billed components, both of which are a bad experience and a waste of resources (These options are also probably against the Shopify ToS).