I'd say that very few logos are not copyrighted, with the exception of
very old ones - and only then in their original form, old enough to be
expired - the modern versions are derived works of the originals and
the modern version has copyright protection for the differences
between itself and any non-copyrighted version.
Given the huge amount of effort companies go through to create a logo
and branding, I think the user is kidding themselves if they think
there is no 'sweat of the brow' involved in a logo. Be that as it
may, German copyright law is not the overriding copyright law of the
project; instead US law in general and Florida law in specific is
(since that is where the content physically resides and where the
Foundation is based). In addition, users must obey the copyright law
of the location in which they reside, but this does not over-ride that
of the Foundation and servers' location.
US copyright law requires a minimal amount of creativity for copyright
to hold - 'mechanical' copyrights do not exist under US law - but
that's an easy bar to clear. Pretty much any logo will pass that
test.
In addition to copyright law, of course, images on Commons must meet
Foundation and Commons policies. I believe it was long established
that we did not consider merely making a photo of a logo made it
magically 'free' where copying that logo by non-camera means would
not.
Photographs of a 3-D object bearing copyrighted design elements are
not blanket prohibited under Commons policy, to the best of my
knowledge, since under most cases these are not considered copyright
violations. However, using such a picture as an 'end run' around bans
on copyrighted logos is generally not considered acceptable, I believe
(e.g. using a Coca-Cola truck bearing the prominent logo as a
surrogate for the logo itself).
-Matt