The Economics of Selling Information:
This may sound like an overgeneralization, but it seems that when you pay to have humans answer your questions, you often talk to so-called experts, and when you get answers for free, you either talk to a librarian, a random stranger, or an open source aficionado. The difference between the Google Answers' model and the public/academic library model appears mainly that when a librarian gives a patron a response to their reference query, the patron tends not to argue with her. If she tells the patron the question has no definitive answer, that response is more likely taken as fact rather than a personal failing on the librarian's part. The fact that all library patrons share the time of the librarians tends to encourage a polite acceptance that each patron's specific question is one of many needing to be answered.
In the Google Answers arena, I have seen researchers insulted, sworn at, and otherwise degraded by people not happy with the responses they received, when you might think that just not paying for the answer would be reprobation enough. Part of the Google Answers standards of conduct include politeness and friendliness at all times and not discussing Google policies or pricing with question askers. Catering and kowtowing to upset customers at the expense of explaining to them that their question was priced too low or phrased too poorly became a trade-off I had difficulty making.
While I enjoyed my time at Google Answers, I was soured by people asking $4 questions and not being satisfied with the depth of the responses they received, responses that had clearly taken a fair amount of the researcher's time. One of the strict rules at Google Answers forbids discussing the amount of money offered for a question. If the questioner offers too little, the researcher should simply refuse to answer their question. Of course, in the competition for scarce questions, this never happened, except in extreme instances. It seemed indelicate or rude to point out to a questioner that if they had placed a higher price on a response, they might have gotten better research and more time from the researcher. Is the customer always right if they want skilled research for $4 an hour? This "customer is always right" philosophy that pervades marketplace interactions seemed to override personal senses of reasonableness in many cases. Google Answers is currently working on guidelines for what kinds of questions most appropriately fit into the various price ranges. Researchers will welcome this tool.
The fact that there are people willing to answer a potentially difficult question for $1.87 does not mean that it is a good idea to encourage people to expect more research for less money, especially when supposedly interacting with experts. The Google Answers system prides itself on having talented workers and yet at the same time encourages — though does not force — them to frequently work for a fraction of the price that degreed, experienced experts could earn for the same work. While determining the free market value of this sort of information retrieval and presentation — most of which is available online, for free — is tricky, my experience working for Google Answers made me feel more often like I was being paid to do Google searches that the questioners didn't have the time or the skill to do, rather than using my research background and abilities to turn facts into actual knowledge.
In summary: There is far greater demand for (paid) work than there is for helpful people. Therefore people fight for paid work even when they don't really understand what they are supposed to be doing. Helpful people are a plentiful and easily "exploited" resource on the internet since having a computer and the time to surf implies a prerequisite degree of financial stability and generosity. Paid work and stingy answers go hand-in-hand. I have noticed that the best answers are often posted by individuals who merely researched the question for themselves. An expert well often post a link to an answer as a comment and then a fellow inquisitor who has more of a work ethic than the asker and more interest than the the expert (who already understood) will write up the answer found at the link. 99% of Stack-exchange questions are answered in books. Taken from this perspective the majority of Stack Exchange questions are reference-requests.
The process of creating scientific journals provides significant insights into the lengths that intellectuals will go to both pursue their interests and pad their resumes with little or no financial compensation. They are the antithesis of businessmen. I think a lot of this goes back to the psychology of melancholy individuals who tend to form a majority of the intellectuals: melancholies love recognition.
Stack Exchange currently is a facilitator in the sense that it lowers the transaction costs between an interested individual and someone more knowledgeable. Instead of e-mailing numerous experts I post a question and the available and helpful ones generously share their expertise.
Prestige is its own reward.
"It is the glory of God to conceal a matter,
But the glory of kings is to search out a matter. Proverbs 25:2."
Oliver Heavenside rejected financial compensation from Bell Laboratories for his work showing that a transmission line wrapped in a conductor has improved efficiency. He was holding out with the stated goal that he be given "sole credit" for the discovery.
Finally: It is more blessed to give than to receive. Helping on Stack Exchange is giving.