Because the detector on their wall was never designed to catch it early. Standard CO alarms are built to a legal minimum, not a safety maximum. They're calibrated to alarm at levels that are already dangerous, which means by the time yours goes off, the exposure has been happening for a while. That's not a flaw in your specific detector. That's how every standard detector on the market was designed to work.
TrueDetect was built around a different standard. One that doesn't wait for danger. One that catches it while you still have time to do something about it.
