A key difference between Android and iOS: on Android, there are alternatives to Google’s app store; on iOS there are not. So it would be entirely possible for

A key difference between Android and iOS: on Android, there are alternatives to Google’s app store; on iOS there are not. So it would be entirely possible for someone who lives in a country where marijuana is legal and wishes to facilitate the legal industry there to set up an app store (cloning F-Droid could be a quick start) which offered such apps. He'd be out of luck on iOS. The federal marijuana laws are — mostly — blatantly unconstitutional, of course, but they are still on the books. I don't blame Google for not wanting to litigate the issue; their lawyers are probably acutely aware of the Backpage case.