Answer:
One of the main reasons why different countries have different currencies is to allow people the possibility to choose the origin of the currency and the goods they want. Imagine if every country in the world would use only dollars. Then every country would be able to print dollars, but the dollars would be same for the US or for Burma or the Congo. Do goods available or produced at the US, Burma and Congo have the same value for everyone?
The US dollar is the most widely accepted currency in the world but the Euro is the most commonly used currency.
