Why are bananas classified as berries while strawberries are not?

In botanical terms, the classification of fruits is based on their structural development from a flower's ovary. The distinction between a banana and a strawberry lies in how they are formed:1

• Bananas are true berries: A berry is defined as a simple, fleshy fruit derived from a single ovary of an individual flower. Because a banana develops from a single ovary and its pericarp (the fruit wall) becomes fleshy, it meets the botanical criteria for a berry.21
• Strawberries are not berries: A strawberry is classified as an accessory fruit and an aggregate fruit. It does not develop from a single ovary; instead, its fleshy part is a greatly enlarged flower receptacle (the tip of the flower stalk). The structures commonly mistaken for seeds on the surface of a strawberry are actually the plant's true fruits, known as achenes.13

While popular usage often labels any small, edible, fleshy fruit as a "berry," botanical classification relies strictly on these morphological features.12