In North America, listings are sent to or uploaded to the MLS System - Multiple Listing System - which is a system set up and run by cooperating real estate brokers - almost all brokers belong.
The MLS System has all of the listings from all of the companies so there is no need for a shopper to go to different companies to see if they have different listings. Any broker can show all of the listings.
Brokers and individual Realtors can get an IDX (Internet Data Exchange) feed right to their website which shows all of the MLS listings - there is no duplication of effort.
Because all of the listings from all of the companies are shown there is no need for buyers to leave the site to check out other Realtors' sites to see if they have different listings.
So, Realtor websites tend to compete by providing other information and services - not just listings as buyers can get all of he listings just about anywhere.
Agents can also set it up so they can display their own personal listings separately in addition to all the MLS listings - useful as a listing tool.
I hope that helps

[This message has been edited by doug (edited 07-14-2004).]
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