Neapolitan forever?

When they're coming up with flavors for protein shakes, why is it always chocolate, vanilla, and strawberry? Doesn't anyone ever suggest, say, steak and potato? Or meat lasagna? Pepperoni pizza? Chili? Mac and cheese? Dorito? Hmm, I think that turned into a list of Things I'd Really Love To Eat A Lot Of Right This Very Moment.