The right question to ask is what do they have in common, and the answer is nothing but an artificial legal construct of IP. To write public domain software you need a computer and 2 sqm of space (or even less) that you occupy while working. Material resources needed to shoot one movie are one big reason you need financial model.
2. math is irrelevant here, has nothing in common with movies or music
3. yes. It’s our culture and our history.