In India there is a color coding system that one sees on all packaged goods and probably a majority of restaurant menus. A green dot in a square means the food is vegetarian (which means neither egg nor meat content in the product) and a red dot means non-veg.
Here in Thailand, at Khlong Toei Wet Market, it’s interesting to see how vendors used red and green awnings. In this case, it’s not so much to signify the product as to enhance its visual appeal. Vendors who specialized in green produce inevitably used green awnings to make their greens look greener. By the same token, meat vendors and fish vendors that specialized in “red fish” (e.g. tuna, as opposed to white fish, say halibut) used red awnings to make the reds redder. Incidentally, white fish and squid sellers often used a combination of white and blue tubs to create another kind of aesthetic appeal. Fruit vendors are out of luck because they have just too many colors to deal with. (Unless they specialized a single fruit like watermelon–or durian, because if you sell durian you’re out of luck on selling anything you don’t want tainted by the smell of durian.)