Why is this the answer?

The answer is smile because this fun riddle is a very clever way to describe something we all have and use every day. Let's look closely at all the clues to see how they point directly to a smile! First, the riddle says: A mile from end to end, yet as close to as a friend. This is a tricky clue about distance. A real smile is only a few inches wide on your face, but the happiness a smile creates can spread very far. Think about how a smile can travel across a large sports field or be seen in a photo sent around the world. So it can go for a mile. But it is also as close to as a friend because your smile is always right there with you, on your own face, ready to be shown. Next, the riddle calls a smile: A precious commodity, freely given. A commodity is just a fancy word for something useful or valuable. A smile is extremely valuable because it can cheer up anyone who sees it and shows that you are happy and kind. It is truly precious! The wonderful thing about it is that it is freely given. You don't have to spend any money or conscious effort to give someone a big, cheerful smile. The following line is interesting: Seen on the dead and on the living. Living people smile all the time to show joy. But how can it be on the dead? This clue makes you think of pictures or memories! When you look at old photographs or watch videos of people who have passed away, their beautiful smiles are captured and saved. The picture keeps the smile forever, even if the person is no longer with us. Finally, the riddle says a smile is: Found on the rich, poor, short and tall, but shared among children most of all. This means a smile is for everyone! No matter how much money a person has, or how tall or short they are, they all have the ability to smile. It is the great equalizer. But it mentions it is shared among children most of all because kids often giggle, grin, and beam with happiness more than grown-ups do. Children are the best at sharing their bright, powerful smiles with the world. All these clues tell the perfect story of a smile.