> With your iPhone/iPad - the OS knows you want to be authenticated because you pick up the device and the device uses that pickup/accelerometer to indicate whe

> With your iPhone/iPad - the OS knows you want to be authenticated because you pick up the device and the device uses that pickup/accelerometer to indicate when to trigger FaceID. Actually, this description is not quite accurate. The phone doesn’t depend on the accelerometer alone. Keep your iPhone on a desk or table and just peek over it (from above) to have it unlock. The trigger here could be a touch on the display to wake it up, or a notification that turns on the display and your face happens to be above it (or close enough with you looking at it if attention is turned on) to unlock and show the notification details (if setup that way). It’s the display turning on that’s a major trigger to keep FaceID ready to go. The larger reason why FaceID may not make it to Macs is because they’re or could usually be shared devices, whereas iPhones and iPads are usually personal devices attached to one user account (I don’t have inside knowledge of Apple’s views on this, so this is just another speculation).