It seems that very answers are accepted here. Are the answers all that bad or do the OP's just not care to accept?
I don't think Dan is asking for a central authority to mark questions as answered; he's just observing that people don't do it here.
Stack Exchange sites work better when users accept questions. It helps future readers be confident that answers are correct, it rewards answerers with more reputation points, and it's generally a sign of a healthy community.
I haven't looked. There's a good chance that most of the questions with good answers that haven't been accepted were posed by people without much investment in this community. Still, a little consideration about how to encourage more askers to accept a solid answer would be worthwhile.
I feel that people not voting enough is a bigger problem. After all, an accept mark does not bring much value to visitors, if answers are already correctly ordered by votes.
So, no accept is not a big problem.
Actually, accepting an answer too early might lead to situations where the accepted answer is outdated (example on StackOverflow). This is especially true for data requests, which is a domain in which the value of answers might change very fast, as old datasets get outdated and new datasets appear often.
The answers on Stack Exchange are not accepted by a central authority. Anyone can post a question or answer directly. Sometimes, questions or answers are flagged by members of the Open Data Stack Exchange community for either positive or negative reasons. For example, members can vote an answer or question up or down, mark as a favorite, or provide a comment.
If there's an issue with the question or answer, any member can flag that item for moderation or removal, vote it down, add a comment, or make an edit. There are three moderators (currently these are Joe, Patrick Hoefler, and myself). We are prompted to look at the first post by a new member or an item that a member has flagged for moderation and address it.
In looking at the metrics since we started, 9 posts have been deleted out of a total of 247 questions. About half of those were deleted by Stack Exchange employees helping us get started and setting the rules of the road.
If you have an issue with a post that has been deleted, please feel free to contact any group moderator for a better resolution. I am personally always happy to help out.