Not all EEs lay blue eggs. Actually, EEs tend to lay eggs more greenish than blue... Anyway, some lay tan eggs or brown eggs just like any brown egg laying breed. A farmer would have to have a whole lot of EE hens to ensure enough eggs were the preferred green or blue. EEs are MIXES. Mixed breed chickens with a wonderful variety of breeds and strains which are deliberately bred to specific other breeds to obtain the "best" color of eggs. Or not, like those in my flock. I am lucky to have an EE rooster which "throws" the green egg gene, so his daughters might also (and have) lay green eggs. All White Leghorns lay white eggs. Easy peasy. The farmer is only feeding one breed which happens to lay only white eggs.