Because the currencies you mention are considered "soft" currencies. "Hard" currencies like the U.S. Dollar and Euro are more widely traded on currency exchanges and are more liquid currencies. Also they are a preferred reserve currency because of the large size and stability of their economies. That's why some commodities like oil are bought and sold in $ or Euro, because the people selling the oil prefer $ or Euro.
Ultimate African Mango

The buying of an ***et today and selling a future contract on the ***et. A reverse cash and carry is possible by selling an ***et and buying a future.
Gamefly