In some libraries patrons are not allowed to add information to library wikis, and a contributing factor to this trend may be an inability or a lack of willingness on the part of librarians to monitor the content patrons could add to a wiki. Users can add almost anything to a wiki, and it is easy for someone to include the wrong information, forget to double check facts, or even spam a page on purpose. It takes effort to make sure the information added by the public is accurate, and different factors such as budget issues, staff shortages, or lack of time could determine if a librarian is able to stay current with edits that are being made to the site.
Another possible reason for libraries not allowing patrons to edit wikis is a simple lack of trust. Since the public can put up nearly anything they want on a wiki, the librarians may think it is easier to do it themselves than to constantly monitor and edit the content patrons add.
Finally, even if they are aware they can add information to a wiki, many people will never try to edit a page. In the library setting, it takes time to organize and implement a wiki. If it is a public wiki and no one ever edits it or adds information, the site may not be successful. Some librarians might feel it is better to complete a wiki themselves and then have access to a reliable resource instead of dealing with the issues that come with allowing patrons to edit a wiki.