The tag summaries for header and footer are also inconsistent - the former refers to the header on a network packet, while the latter refers to the footer on the page of a website/document.
It's possible this isn't an issue, but do we really need footer? To me, it seems like a fairly basic layout function rather than something that needs its own tag.
Quick list of the various uses of header:
Simple content at the top of a page:
C++ headers and how to include them:
And yes, there are a some questions about HTTP headers as the tag wiki suggests:
Although many seem to deal with specifically with the 'headers already sent' error message in PHP:
Although these are all related in the sense of including something at the beginning of something else, I think header especially is acting as a meta-tag, despite its specific tag-wiki, made worse by the fact that so many of the issues are those that plague beginner programmers.
It would be a hell of a retag operation (there are currently over 5,000 questions tagged with it) - would any meaning be lost if the tag were simply burninated?