[who_would_fardels_bear]

Also, the ones that get installed with new construction are usually the cheapest bottom-feeder brands that go off when there is no CO and remain quiet when there is.

And there're enough cheap, crappy units on the market that people are reluctant to pay the price of the few brands that actually work.

[wrench]

Absolutely correct.

A quick amazon search shows some real cheap chinese made units. A half a dozen different “brands” but obviously the same manufacturer.

Laws (building code) require smoke detectors in the US, but the quality is up to the builder. Inspection passes as long as it is screwed to the ceiling/wall. No quality control, and no ops check required.