At least for apples, that's due to the feedback loop from the super market. 1. New variety ( red delicious, gala, fuji, honey crisp) 2. Customer says, "I real

At least for apples, that's due to the feedback loop from the super market. 1. New variety ( red delicious, gala, fuji, honey crisp) 2. Customer says, "I really like it! Could you make it redder?" 3. Farmer/nursery selects for apple strain that is redder, implicitly deselecting all other characteristics. 4. Customer selects red'est version of variety in the super market and passes up less-red variety. 5. Non-red variety taken out or grafted over in orchards to super-red variety. 6. Customer says, "I don't know why, but I don't like the taste of galas anymore!" 7. goto 1