That's just one of the many rules of handling business cards around the world. When traveling, take time to study the proper etiquette of business cards, lest you are considered a boorish American.
Business cards play a very important role in trade.
Given the fact that most companies spend a great deal of time and money designing their business cards, it makes sense to treat them as an effective business tool. Take your time while handing your card to people. In many countries, it is considered an insult for a guest to be the first to proffer a business card. If at all possible, have your card translated into the local language. One side of the card should be in English and the opposite side in the local language.