$0.20 is the minimum, you pay for every device they install on every time. Anytime they offload and reinstall, you pay again. Every additional device, upgrade, or replacement, you pay again. You’ll also pay then current rates, whatever Unity decides those are.
No abuse needed to lose money with this, I’ve probably installed the same games 20+ times over the years.
They can probably track accurately enough to identify that 90% of games aren't worth billing. Then once they are working with the top 10%, they can negotiate something that makes sense, like submit your monthly sales number, and Unity will use that as a limit on install count.
I agree what they are saying isn't workable, but that idea of install based fee could work, and would be better than a royalty for many.
No abuse needed to lose money with this, I’ve probably installed the same games 20+ times over the years.