You're picking a very odd target for this in Apple, who are pretty clear about their attitude on privacy, especially when it comes to cameras and microphones - for instance modern Macs and iPads have hardware disconnects for the microphones[1] when closed & Macs have green indicator LEDs wired into the camera hardware to make it impossible to activate the camera without the light coming on (as noted in the article we're commenting on!)
Also, you're still talking about FaceID: the parent comment pointed out that FaceID doesn't exist on the Mac. Craig Federighi was actually asked about FaceID support for the new notch Macs when they were released, and he said that he didn't think there was a benefit vs the TouchID sensor because it'd still be necessary to have the user tap a physical button to confirm actions -- e.g. for purchases or privilege escalation. The camera assembly would also need to be thicker & larger to put the FaceID projector & IR camera in place.
On using continuously (and surreptitiously/illegally) captured camera data to improve FaceID's model of the owner for iPhone/iPad: there's just no need to continuously capture - there is already plenty of opportunity to update the face model every time the phone is unlocked. I don't know what the stats on this are but I'd imagine users are unlocking their phones hundreds of times a day.
>It can also help to improve facial recognition in photos which Apple has been featuring for some time now in their Photos app.
They already have lots of data here from your photos already, and since they're stored in your photo library your Mac has access to them to re-run recognition if needed if an updated version of the Photos app comes with a model update. Not to mention that by using above-board data they are able to get corrections for classification errors (since the user operating/looking at the computer may well not be the account owner).
1: https://support.apple.com/en-gb/guide/security/secbbd20b00b/...
