I don’t know if it’s still the case, but when I used to read up on video cameras, the sensors used a Bayer pattern that had twice the resolution for the green channel as the red and blue channels. This leads to the green channel having more detail for chromakeying.

“Invented by Bryce Bayer at Kodak, the Bayer pattern dedicates more pixels to green than to red and blue, because the human eye is more sensitive to green. The additional green pixels produce a better color image.”

Bayer Pattern Sensors