Apple is being disingenuous. The App Store didn't "generate" those "billings and sales". That number includes physical goods and subscriptions that didn't go through Apple.

They used to report this number as sales they "facilitated". A far more accurate descriptor. But now that they are engaged in a PR battle with various governments they have taken to embellishment.

https://www.apple.com/newsroom/2020/06/apples-app-store-ecos...