Real lemonade is inherently kosher
Just to be clear, the makers of “Simply Lemonade” didn’t decide to make their product kosher — it is inherently kosher, as it contains no animal products. What they chose to do was to have that inherent kosher status “certified” by a kashrut authority, enabling them to market the fact that their product is inherently kosher. This certification is valuable to Orthodox Jews, but also to anyone who chooses to avoid consumption of even trace amounts of animal products. Oh and by the way if it were 100% lemons it’d be lemon juice, not lemonade — lemonade always contains water and sugar.