Android phones, apps and tablets

Both.

Copyright is a relatively recent invention to earn from a creative work after the work has been completed.

Before copyright one was traditionally commissioned to create a work. I tend to think of architects as a simple example, they are paid generously in advance for the creation and it's execution, but they don't assert a right over the creation once it is there and don't assert any claim to an income derived from it's use or resale or even from someone creating a derivative work.

I just do not see why copyright exists at all.