TerryL, there is not a simpler explanation - unless you are being sarcastic.
There cant be one world currency as that would not relieve any pressures. Economics is all about supply and demand. If there was one currency it wouldnt take into account different governments' interest rate changes. Governments can not always make the same interest rate changes as pressures on inflation are different in different areas depending on the level of economic activity being experienced there. Prices need to be somewhat stable (inflation low) so people and businesses can plan and make rational choices regarding the future.
There cant be one world currency as that would not relieve any pressures. Economics is all about supply and demand. If there was one currency it wouldnt take into account different governments' interest rate changes. Governments can not always make the same interest rate changes as pressures on inflation are different in different areas depending on the level of economic activity being experienced there. Prices need to be somewhat stable (inflation low) so people and businesses can plan and make rational choices regarding the future.