Well, bananas takes days to get, picked, contained, shipped and distributed throughout the US. If you picked a ripe banana from the tree, it would show up in the grocery store completely brown. If it shows up unripened, you can place it in a paper bag for a day. It does not contain any less potassium if it is picked off the tree earlier.You can even get screwed at the produced department, because fruits and vegetables are harvested before they are ripe. If its not ripe it doesn't have the nutrients of a fully riped fruit or vegetable.
Big corporations do not feel food is about sustenance.