Once upon a time I had a Viewsonic monitor that had a Pantone calibration card. Very nice monitor. Not terribly expensive but more than middle of the road.

Lots of monitors can calibrated. Expensive ones will provide a way to do it properly (e.g. puck and software.)

Over the span of time it would take to check the entire population, the backlights or LEDs or OLEDs would start to wear out, slowly affecting the results. 😅

Yeah, that's right, but the main problem that I see with that is that those people will be biased from the "real" green or "blue". I checked the site, and it says that a lot of other factors can affect how people perceive its monitor light.