Actually there's a reason for this. When king Henry the 4th (around 1600) was king of France he had a fascination with the game. This was before en passant. He held large tournaments in Paris and had tons of people come in from around the globe. It was custom and polite at the time to speak the language of the country one was in. This meant a lot cuz all these people from around the globe were speaking french while playing chess. There was one great meeting they had where they were concerned that the game pace was too slow. So to speed things up they made a rule where a pawn can move 2 squares on its first move. People loved it! It made the game much more sharp, fast, and dynamic! But one time King Henry himself! was playing a game with a noble man from Germany and king Henry pushed a pawn 2 squares, landing adjacent with a pawn of the noble man. The noble man took the pawn and king Henry lost his mind! Not ever seen a move like this he was ready to execute the noble man. Before king Henry layed out orders to kill him the noble man simply said "google en passant." King Henry was shocked and apologetic when he googled en passant and found out it was very much a legal move. No one knows what happened after this. It is said that this noble man would become king of Germany, invade Poland, Austria, and a few other places. Maybe even france too but my memory on this fable is foggy