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?

Because they're disrupting thermostats.

Success.

the team consists of a bunch of industrial designers and *hitty electronic engineers?

This is why I like the FirstAlert wireless detectors: mesh network so they all go off, but you program each one to announce with a voice which room the trouble is in. They even announce which one has the low battery instead of chirping in the middle of the night.

Well much of that was the "dream" of the nest protects...

It announces where the "alert" is, you can wave to dismiss it, it has the app for your phone to alert you if you are away from home, and they all link together (without needing any wiring in the house, making it easy to retrofit).

Sadly in practice it's a mess, nothing works, so much so that I've lost all confidence in the product to do it's minimal function, detect smoke...

It's a bit ridiculous when you could have basically taken any old mass produced el-cheapo smoke detector circuit, and instead of tripping an alarm have it just feed into gpio pins on some wifi/whatever controller that has the "smarts".

Literally all that was needed to get 100% of the reliability of the billions of detectors out on the market, while working out all the kinks on the "cloudy" sort of stuff.

I have to admit I re-invent the wheel more than I should, but man. This one seems simple :)

Here is what I think is a sane timeline:

(1) smoke detector in kitchen goes off, only sets off in kitchen

(2) after 1 minute, other rooms start saying "smoke in kitchen"

(3) after 2 minutes, alarm goes off in other rooms

Timeline could be shortened if necessary for safety, but this doesn't seem like it would be difficult to implement.