Music is mainly purchased through aggregators like iTunes and Spotify who charge a hefty tariff. You need a comprehensive catalog to convince users to commit to a payment relationship.
In-app payments on iOS and Android are the one place where paid snacks exist at scale. They have been wildly successful, quickly becoming the dominant business model for games, replacing up-front payments and banner ads. (There are individual games that generate over one billion dollars per year from in-app payments.) Outside of games, entrepreneurs have started building interesting new products that wouldn’t have been viable without in-app payments.