Why can't I use sample avatars in my app for display, other than tools?

Question

activity_main.xml

<ImageView
    android:id="@+id/image_view"
    tools:src="@tools:sample/avatars"
    android:src="sample/avatars"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:scaleType="centerInside" />

Answer 1

I guess since sample Avatars are not really drawable image assets. Hence, we can only render them on a tool setting (not built apk).