Now, their friends all have iphones, and if a kid could hack out an app for their friend group and share it around, it would give them great motivation to learn and hack in that ecosystem.
It's kids, idealistic OSS hackers, and people in the global south who see the $100/year and give up.
It's also just plain dumb rent-seeking that no other OS does. I can make an APK for a friend for free, I can make an exe for a friend, an elf for a friend, etc.
Yet, even if I live in the EU and thus can distribute apps to my friends to sideload directly, even then I'm required to pay $100/year or my app stops working.