Originally Posted by ATimson
I think the "problem" here is that the Kindle app will display the cover image specified in the cover <meta> tag when you open a book. With an ePub, you need to specifically include a separate HTML page with the cover in the spine in order for it to appear when you open the book in most readers.
That said, my understanding of ePub cover best practices
is that you shouldn't
be showing the cover when you open the book - tell the reading software how to find the cover, but let it decide whether or not to display it.
What the threepress link says is:
Ensuring the widest interoperability for your cover means including an XHTML cover page (as the first “flow”), a cover image, and bits of OPF metadata to refer to these items using consistent names.
Which agrees with your original point, that for an ePub the "cover" needs to be the first item in the flow. When Calibre converts a MOBI to ePub, for example, the MOBI cover is put on the 1st page of the ePub.