The Mac camera light is wired inline. If the camera is on, so is the light. Since we're not seeing the camera light flashing on periodically, this isn't how it's being done.

The Macbook tally light isn‘t necessarily wired to the camera. It very well could be independently software controlled. At least it was not too long ago. IIRC there was an article about this, posted here on HN.

Macs used to have (still have?) a feature where you could declare it as lost/stolen and remotely take a photo with the camera. I believe the light didn‘t glow for that.