Apps follow the AppStore law. Apple follows US law. And the later includes some social aspects like Anti-Trust laws, consumer rights, etc.
Companies exist in a nation. A nation serves its citizens. So when a company is treating the citizens bad, a nation has all the rights to enforce whatever is needed. Hence antitrust laws.
This seems a bit disingenuous. A more accurate take might be that you sign up for the Apple developer program, and in doing so agree to the terms of service including the cut that Apple will take from each sale. Then you begin working on the app, then you release the app, then Apple keeps the cut that was contractually agreed upon. There is no stealing, and anyone that puts in years of effort into an app is surely aware of the cut Apple takes before making that effort.
Sure, they're providing a service but that service is only necessary because of the mafia's market capture and threat of punishment in the first place.