When I was authoring software (over two decades ago) and a company acted as publisher they took 85% of gross.
For author/publisher relationships at that time, this was pretty typical (book authors/publishers being the closest analog).
Needless to say there was, in addition to the cost of creating and shipping floppies, advertising that the publisher had to cover.
Apple's 30% cut seemed fair to me when the App Store arrived.
I'm not sure if I would try to ship an iOS app these days though. Not because of Apple's cut but because of the race to the bottom that was unleashed shortly after the App Store gold rush: where now you don't appear to even be able to sell a $0.99 app.
The other problem is of course that no one else can really enter this space. It's now only Apple and Google. It will be very hard for anyone else to enter. There were many more publishers and the competition and differentiation was higher.