If it was all rights reserved, why did they publish it? Did they had an
agreement with the photo database to only provide them photos which they
would be allowed to publish?

I assume they had. How the image went to come in such a database withour the information totally beats me, though.

Do you mean by uploaders before uploading, or an automatic
transformation by the software?

The later then raises that the software doesn't really know which
license has each image. We could add to thumbnails a generic "go to URL
foo to know about author and license terms".

Yes, at upload time, automatically. It should be possible to request that a fields "author" and "licence" be filled and to automatically update the corresponding EXIF tags if they are void. Or even to have some elementary data-mining component that would extract the data from Template:information and such things.

And maybe advertise the issue to users, pointing to easy ways to EXIF-tag the images.

-- Rama