Setting aside the emotional and volatile aspects of the colour...

To my eye the dark areas of Mars appear steely-blue, not green. I can confirm that spectral analysis essentially agrees with this.

To a first approximation, the dark areas of Mars are Black, with a hint of blue. This can be supplied by Haematite (gunmetal).

There is some comment in scientific circles that Olivine has been detected. I remain as sceptical of this as any other claimed IR mineralogy. However, if it were true, some green-yellow colours might be expected.

Hard to tell these from Chlorophyll without very high spectral resolution!

(That doesn't mean I support "Chlorophyll on Mars" Just that I'm offering a defence for those who claim thaey have seen green!)