I’m sure it’s just a software thing, because even with the flavor mix-ins, they didn’t give you every possible combination at any I’ve personally used.

Click Coke, you get Coke, Diet Coke, Coke Zero, and then, like, Vanilla, Cherry, Lemon, Lime, etc flavors. Click Sprite and now the only flavor options are Orange and Cherry. Why the hell can I not have vanilla sprite? Why are all the other soda options not also a mix-in flavor option? Make it make sense!