It would be interesting to see another chart using volume or weight to compare nutrient values instead of calories - 1 pound of greens vs 1 pound of chicken etc... Last night I ate a huge organic salad that came in a clear plastic container the size of a large shoebox. I ate the entire salad but it was only 80-100 calories for the entire box. I would have to eat 20-25 large boxes of these salads in one day just to get 2,000 calories into my diet for one day - no way that's happening. Meat and fat add the caloric density to complement greens.
I have settled on a meat and greens diet (no grains, no dairy) and am doing very well on it. I do believe humans thrive as omnivores, not just survive. There is something about combining the right healthy meat and greens, plus the right fat, that gives a synergy and energy that a mono-diet can't provide like with fruitarians or even vegetarians. The human brain thrives on certain amino acids, enough amino acids, and related nutrients that can rebuild neurotransmitters like dopamine and serotonin.