When Google started in 1998, it was different from other search engines of the time for a number of reasons. Most search engines ranked websites solely by the number of clicks each website had. Google decided it could provide value to its users by providing more relevant content.
The way they achieved this initially was by ranking websites by the number of inbound links it has coming from other popular websites. It is still the main factor influencing how a website gets ranked in different search queries. Google has a "black box" with unknown search algorithms that change frequently, so no one outside of Google really knows completely how ranking and relevance is factored at any given time.
I have found the majority of real estate agents and many other small businesses do not have much of a web presence, so those that do are handsomely rewarded. If you are a small business owner, you have got to have a professional website and inbound links to it from other established, relevant websites. Web marketing is like the Wild West right now, so I suggest you claim your stake.
Note: While I can appreciate Google's strive for excellence, it is frustrating to me as a real estate agent and small business owner that my website ranking fluctuates so greatly. When you search for Overland Park Real Estate Agent my website is in the top position, but as recently as 6 weeks ago I was not even in the top 10. I have noticed similar patterns in several searches neighboring cities as well as for my home search of Prairie Village Real Estate Agent.