Why does the tutorial for creating a demo app, https://source.android.com/docs/core/virtualization/writeavfapp https://source.android.com/docs/core/virtualizati

Why does the tutorial for creating a demo app, https://source.android.com/docs/core/virtualization/writeavfapp https://source.android.com/docs/core/virtualization/writeavf..., only work on Cuttlefish (emulator)? Nevermind, only the demo app, not the tutorial, so who knows what its doing.