I'm not saying people should be keeping stock on-hand. I'm saying that their current system is clearly malicious compliance as all that admin also costs them more, so the only reason I can see is extra annoyance to make self-repair less attractive (and prevent third-party shops from using this program as a source of genuine parts).

> Returning cores for a price rebate is a totally standard industry practice.

Depends for what. A worn down (or outright destroyed, if you screwed up and couldn't get it out intact) battery has zero value beyond its raw materials, which are much less than the cost of shipping it back (the eco-friendly option here is to drop it off at a local recycler which will collect and ship them in bulk).