Yet industrial/commercial grade hard wired smoke detectors work just fine. I've worked in industrial facilities where there were thousands of smoke and fire detectors, and a zero false alarm rate. Yet, one day, when a HVAC unit overheated and smoked, all the right stuff happened. The local alarms went off, and the duct dampers slammed shut to contain the smoke. But because there wasn't confirmation from a second detector, or water flow in the sprinklers, the full emergency power off and building evacuation sequence didn't trip. We got to the HVAC unit and pulled its main switch before things escalated.

So why can't Nest meet that standard of performance?