Question

Why is lemon juice prepared with artificial flavor and color whereas a dish cleaning gel made with real lemons?

Answer 1

Bottled lemon juice is used for the purpose of its sour flavor.  It's usually mixed with something, and its primary purpose is for its sour flavor.  It does a reasonable job of passing for lemon juice, which for the most part just tastes extremely tart.  Really, people who buy bottled lemon juice are buying into the convenience and not the flavor.  

With respect to the 'natural lemon scent' in dishwashing detergent, the nose is much better at distinguishing between odors than the mouth is at tastes (although they really work together).  Thus, an artificial odor would smell artificial.