A torque wrench set does come in both systems. Indeed, the better systems actually have both indications on the wrench and have heads that will take either US or metric diameter systems. The reason that torque wrench sets come in both systems is that while the auto industry had its birth in Europe, (the United States and Great Britain at about the same time,) the European industry was slower to develop and had not yet fully adopted the metric system yet. The U.S. or British system of inches and feet was the standard used until the imports became a serious player in the U.S. market about 25 years ago.
For more info, see Auto Ratchet Set: US or Metric? Which One Should You Buy