"Tooling for compliance" sounds a hell of a lot more complicated than "you sell my app and send me a check", which is the deal on the App Store, Steam, etc.
Finance and compliance is lot more complicated than send me a Cheque for most businesses.
Stripe ( and others) have products right from incorporation (Atlas?), identity verification, custom reporting, fraud/risk, Charge backs, Tax reporting/ filing and even PoS terminals etc.
Most businesses have to deal with multiple channels (Android, web, iOS and others), custom reporting, and different risk/compliance will need solutions well beyond what Apple is offering
