[skyzyx]

This is what Google’s and Apple’s (and Nintendo’s, and Microsoft’s, and Sony’s) cut covers. They built the platform, the system, provide straightforward billing, provide the “shopping mall” that draws eyeballs, etc.

It’s not just payment processing.

Fair fees for the exchange of value they provide is perfectly valid and fair in capitalistic societies. The percentage number is up for discussion, but “charging for value” by the platform vendors who built the thing and provide the platform itself is a valid point.