Looking at flashlight runtimes on battery, it seems like white LEDs (blue with a phosphor) or blue, are much more efficient per lumen than any other color. Perhaps that could be a reason as well? I'd generally prefer green and red.
I expect that has to do with the properties of the human eye, and the fact that the lumen is defined in terms of those properties. I doubt white LEDs are significantly more efficient than any other color in terms of EM flux per watt, but a relatively large proportion of those emissions are at wavelengths to which the retina is sensitive.
