Markets need participants, capital, liquidity, effort, etc. to become efficient. A lot prediction markets suffer from the fact that volatility in them is limited and that the outcome is not of interest to many people, so the markets cannot really do what markets are supposed to do.
If markets are aggregating crummy data and information, no useful market will form. And that is observable even in much more developed financial markets, where some things really have trouble on price formation. And then you might use auction methods, for example.
Similarly, if stuff happens rarely and you only get very limited shots at being right, then averaging and aggregation or not so useful because you cannot get an average (e.g., can do one thing for the next five years and better be right, for example).