Warden snow bias - eye strain and migranes
I recently played warden a bit on able (I know eww but I wanted a chance to have fun), and noticed that the headaches that I would get after 11+ hours of scrooping were more muted and delayed than when I play colonial. I was able to play for longer and felt a lot less burnout, so I decided to do some research on why this could be. Since I play a lot in the backlines, I figured it could be something to do with the terrain and environment.
Now there are already a lot of advantages that devman has given the warden environment, such as the lack of tall grass making partisans easier to find, wreckage and scroop fields easier to spot, and mountains providing easy win chokepoints. But I came across a much more likely psychological phenomenon: white light gives you less eye strain than green.
Human photopic vision actually peaks around green light (~555 nm), meaning green colors appear brighter than most other colors at the same intensity (photopic vision). That also means stronger retinal fatigue and afterimages from staring at my monitor for hours at a time, usually magenta/pink afterimages caused by cone exhaustion (retinal fatigue / afterimages). After enough scrooping, that constant green and purple really overstimmies my eyes.
If that wasn't bad enough, most RGB displays allocate additional luminance contribution to green because the human eye is most sensitive to it. This is a fundamental part of luminance encoding and modern display standards (luminance encoding). So the already bright colonial environment is effectively being amplified by the hardware itself.
Now that we've established that green is more visually intense than snow, let me introduce chromatic aberration. Different wavelengths of light focus slightly differently in the human eye, and highly saturated colors can create uncomfortable depth/focus effects and visual fringing (chromatic aberration, chromostereopsis). This effect really puts the cherry on top when looking at grass for 11 hours straight.
I am completely certain that devman discovered this during playtesting and player telemetry analysis, and once again chose to give the NPC faction a physically harder gameplay experience because it better fit the lore of their favorite faction.