Fairly sure all cultivars are the same species. And I dunno about you but I regular see Lady Fingers and Plantains and not occasionally Red bananas at markets here along with the ubiquitous Cavendish, so they obviously are eaten (I've had cooked Plantain in south American dishes a fair bit, but not recently).
But it's probably true that most fruits are more heavily dominated by a single cultivar than apples, and there's rarely more than 2 or 3 alternatives readily available. Esp. berries - can't think of when I saw multiple options for blueberries or blackberries and even for strawberries it's rare to have much choice.