I must admit to never having been a Piezo user, given that there are open source methods around to achieve a similar outcome. Nonetheless the app has proved popular among Mac users because of the simplicity it brings to the task of recording application audio.
Rogue Amoeba, the publishers of Piezo, removed their app from the App Store thanks to the restrictive T&Cs. The app has been sold only from the Rogue Amoeba website for the last year.
Counter-intuitively it turns out to have been a financially sound move. Whilst sales have fallen off slightly revenue has actually increased, the reduction in sales being more than compensated for by the removal of Apple's 30% cut of the selling price.
It's interesting to note that users are still able to seek out the software they want, without the nannying of Apple's regulators. Also that users are happy to pay a fair price for a piece of software even without the 'security'conferred by purchasing from the App Store.
By selling through the App Store Rogue Amoeba were actually cutting themselves a worse deal - giving Apple a 30% cut for exactly no value.
It would be interesting to see the numbers behind Rogue Amoeba's graphs to establish what the break even point would have been in terms of Apple's cut. But I can't help wondering how many Mac developers are similarly denying themselves an income in order to support Apple's bottom line.
How that same argument plays out on iOS remains to be seen, unless the EU or US Competition regulators force Apple to allow sideloading of apps and app stores, in the same way that Google does, iOS developers have no way of knowing how much of their income is being given to Apple for no reason.
For now, this seems like a good reason for not distributing MacOS apps through Apple. Even if Apple is likely to make it more and more difficult for customers to install apps outside of the Store as time goes by.