Why "auto-on, manual-off" isn't just a setting preference — it's the exact wording several energy codes use to tell you which one you're legally required to install.
Ask most people the difference between an "occupancy sensor" and a "vacancy sensor" and they'll assume it's two different products — maybe one is more sensitive, maybe one costs more. In the overwhelming majority of installations, it's the exact same PIR, ultrasonic, or dual-technology motion sensor hardware. The only thing that differs is a configuration setting buried in the sensor's programming: whether the automatic-ON function is enabled or disabled. That single toggle is why energy codes like ASHRAE 90.1 and California's Title 24 name one of these configurations explicitly, in specific space types, instead of leaving it up to installer preference.