I can see your confusion. There is a perfectly good explanation for this situation. All journals are different in terms of their citation policies. Most journals give all the information right in the beginning - author, date, journal volume and whatever other information is needed. However, not all journals follow this pattern. I have seen several journals that do not give the author's names until the end, even if the official citation is on the first page of the article. It is just a matter of the preference of the journal editors.
Another possible reason for this can be due to the fact that the article is part of an edited book. If this is the case, the author probably would not be in the front of the article at all. The same would go for an encyclopedia of dictionary articles. In fact, in these later ones, you might only find the author's initials. In this case, you would have to go to another page to find out the author's name.
In short, citations are a matter of which convention the editors decide.