What is the origin of the 15-30-40-game counting - why not just 1-2-3-game?

The 15-30-40 scoring system in tennis likely originated in France, where the game was first popularized. The use of 15, 30, and 40 may have come from the practice of using a clock face to keep score, with each point representing a quarter of an hour. The term "40" is believed to have been used instead of "45" for easier pronunciation and to maintain a rhythmic flow in the game. This unique system distinguishes tennis from other sports and adds to its historical charm.