That would still mean that Apple would need to have a remote way of scanning every device currently connected to your account (even it's offline..?) to see if you have the app installed anywhere. It's trivial if the app can only exist on a single device and that is the only device that can request the refund. But that's not the reality.
I mean they already track which device things are install and not installed on, a simple popup "please delete this app from all your devices in order to request a refund" would be all it takes .
Or if that's too much of a disruption for users, just requiring the current device to delete it would cover most cases and be better then the current situation.
Users can set each device to automatically download and install newly-purchased apps.
Imagine the case where there is a device you have misplaced (or given to a relative, or had stolen, or ___). You must find every device with auto-download and purge the app from each one before requesting a refund.
So you create a situation where it is possible that the user quite literally can't comply with the terms of the refund.
Perhaps a compromise would be to
1. Delete from the current device; and
2. To verify the status of each app during OTA updates (which, by definition, have connectivity to Apple's servers). Any refunded apps would be greyed-out or something.
It is trivial to track that an app has never been opened on a device and automatically uninstall it in that case. Seems weird to fall all over the notion that 'oh no! apple can delete my apps remotely!' - but you're fine with 'apple can install apps remotely'.
Uninstalling an automatically installed, never-opened app is not a breach of the personality of your device.
