There's no easy way to tell what the markup corresponding to this image is, because it's a redirect. The mouse-over text brings up the name of the target file, not the redirect version. In a page crowded with markup, it's helpful to be able to see the name of the file as it's actually written on that page. Also, since redirects are used to provide descriptive file names in others languages, it would make sense for the redirect name to be displayed as mouse-over text, and for there to be a "redirected from" link on the Wikipedia version of the image page.