You are more correct than you know. “Coke” (the full sugar, red can kind) is actually Coca-Cola “Classic.” Notably in the 80s Coca-Cola reformulated to the absolute outrage of the soda drinkers of the world (1985). They had released a diet version of this reformulation three years prior (1982)—I suppose as a trial run—based on Tab. For some reason people liked the diet version. This is Diet Coke. After
backpedaling on the reformulation, the full-sugar flagship was re-released in all its former glory, dubbed Coca-Cola Classic. Much later, a diet version of this “classic” formula was released. This is Coke Zero. So yes, it’s absolutely about taste, because Coke and Diet Coke aren’t based on the same recipe!