If an answer is bad, it is sometimes possible for anyone to see that. But in order to say that an answer is good, I would say that that ALWAYS requires knowledge within the field.
My spontaneous thought is something like a tag badge on SO. For those who does not know, You’ll get a tag badge when you have received enough upvotes on your answers. So in order to get the privilege to upvote, it is reasonable that you somehow prove some knowledge about the topic first. A similar approach is making votes from people with proven knowledge within the field count higher.