I think what you're missing is that this is likely in preparation for some sort of AR glasses and something smaller form factor than the Vision Pro that will require transparency so you can see through to the real world etc...
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If there is "some sort of AR glasses and something smaller form factor than the Vision Pro that will require transparency so you can see through to the real world", limit the transparent interface only to that device.
Mark my words, this is coming. It’s doable (as an effect) - rear camera captures what’s behind the screen, face tracking adjusts perspective in real-time to make it seem transparent/have correct parallax.