Why do businessmen use the dollar bill in international trade?

Answer 1

When someone says that "the dollar is used in international trade" that doesn't mean physical paper money is exchanged (especially $1 bills, because they're so low in value). It means that prices of goods, services, etc. are generally expressedin dollars.

There are a number of reasons for this. Probably the most significant one is that the US economy is considered to be one of the most - if not the single most - system among all major countries. In addition it's one of the largest economies with connections to other major economic powers such as the EU, China, Japan, Brazil, and so on. That breadth and stability gives other countries assurance that goods priced in dollars can be traded fairly and with minimal variations.

Another reason is that when the current world economic system began to form following WWII, the US was the only major country whose economy and infrastructure had survived relatively unscathed. While other combatant nations on both sides such as Britain, France, Germany, Japan, and the Soviet Union faced decades of rebuilding the US was able to return to peacetime production much more quickly. American goods and services formed the core of post-war recovery, so making transactions denominated in dollars was quite common.

Today the dollar remains the most important currency for international trade, but it's being challenged by the currencies of other mature (or maturing) economies such as the EU and China.