That's not really an Apple tax though, that's a cost of doing business tax. It's not like Intel and AMD and everyone else aren't effectively doing the same exact thing.
Apple probably does the same strategy PS3 did: create a 1-PPE + 8-SPE chip, but sell it as a 1-PPE + 7-SPE chip (assume one breaks). This increases yields, and it means that all 7-SPE + 8-SPE chips can be sold.
6-SPE-chips (and below) are thrown away, which is a small minority. Especially as the process matures and reliability of manufacturing increases over time.
You can read more info on this forum post: https://community.amd.com/t5/processors/ryzen-5900x-system-c...
Thank you.