I've read it and it states it is not an useful metric and, please correct me if I'm wrong, does not say anything about measuring fake plants. As far as I understood, it does use the reflectance in red and infra red to detect soil, water and vegetation, but it was not designed to detect fake green plastic from plants anyway.

I mean, who would think someone would use fake grass and fake plants and also use paint in mountains. It is so stupid that no one would even think in measuring it.