I suspect they're charging $0.50 on alternative app stores as well as their own to be able to give something during the inevitable negotiations with the EU: "OK

I suspect they're charging $0.50 on alternative app stores as well as their own to be able to give something during the inevitable negotiations with the EU: "OK we'll stop taxing other stores, just let us keep taxing ours" Straight out of the claim-enormous-damages playbook to anchor the figure higher.