The reason why the three credit reporting companies in the United States of America has simply got to do with the way things developed over the period of time.  Credit reporting had its birth more than a hundred years ago.  When the system was not so organized and unified individuals went to different merchants in different towns and cities collecting information about the credit behavior of individuals and how they repaid their debts.  The benefit to the lenders and the margins even at that point of time was that they could then ask for a reference based on the information present on the local credit bureau files.

Eventually with the advent of time and as with any other business and industry credit reporting expanded got automated and consolidated into three regional credit reporting companies.  Experian involved in the West and is now based in California.  Transunion based in Chicago expanded its business in central United States and Equifax based in Atlanta spread its business in the South and East.

When the system got computerized and the scope of communication and maintaining database on a national level developed all the three credit reporting companies gained national scope and became competitors.  While all three of them serve the same basic purpose the ancillary services and customer the links differ along with the list of clients that they have.

Just like any other business that manufactures the same goods and services but has competitors in forms of other companies doing the same thing where one is not necessarily worse than the other part more matter of reference on the part of the consumer, credit bureaus also compete amongst each other while providing the same service of credit reporting to the consumer and business.

It is normally a belief that competition in any field is good for the overall business as it provides more beneficial terms to the consumer and avoids monopoly by a single service provider.  The same probably holds true for the credit reporting companies.