> and no firmware is involved in enforcing the LED stay on for 3 seconds after a single frame is captured.

I may be the oddball here, but that 3 second duration does not comfort me. The only time I would notice it is if I am sitting in front of the computer. While someone snapping a photo of me while working is disconcerting, it is not the end of the world. Someone snapping photos while I am away from the screen is more troublesome. (Or it would be if my computer was facing an open space, which it doesn't.)

Right, so this is all defense in depth. That LED is sort of the last line of defense if all others have failed, like:

The exploit mitigations to prevent you from getting an initial foothold.

The sandboxing preventing you from going from a low-privileged to a privileged process.

The permissions model preventing unauthorized camera access in the first place.

The kernel hardening to stop you from poking at the co-processor registers.

etc. etc.

If all those things have failed, the last thing to at least give you a chance of noticing the compromise, that's that LED. And that's why it stays on for 3 seconds, all to increase the chances of you noticing something is off. But things had to have gone pretty sideways before that particular hail-mary kicks in.

OK, but then what? Leave the LED on for 24 hours after you've captured a single frame? At that point the LED isn't really indicating camera usage because you'll just get used to seeing it on all the time whether the camera is in use or not.

It's strange that none of these companies will include a closable cover for the camera. I got one aftermarket. It is very reassuring since no hacking or accidental misclicks on my part can move the cover.