The idea is to build a knowledge base with one +/- authoritative answer to a question that people can refer to after some time. You have sql or api access and can do a real statistic, I can only browse, but looking at the last days e.g. I don't see many questions with approved answers.
Answering is one part, the other is giving the feedback if the answer was useful and this should be reflected somehow. And yes, I tend not to answer question for people that I see just asking and never approving. I conclude (premature and without evidence), they are also not voting, just asking.