It is rare to find a truly free and open market where all participants are equally informed. In many cases there are some with inside information and thus, advantage. While free markets are an ideal to seek, it is not realistic to believe they can always be achieved. Betting markets can increase transparency as people with inside information are incentivized to participate. But what is required is some other hand than that of market forces and gambling - ie freedom of speech and sometimes, regulatory oversight! "People of the same trade seldom meet together, even for merriment and diversion, but the conversation ends in a conspiracy against the public, or in some contrivance to raise prices."