This may actually belong in bug reports and not feature requests though!
I’m looking at the headers of the pages you link to and it looks like they have both twitter cards and open graph tags already in the header. This suggests to me that people have already tried to implement twitter cards but either didn’t complete their implementation, or perhaps didn’t test it fully out for these pages.
I don’t know how the moderators classify these things but my intuition here is that this is more a bug report than a feature request.