Peter Ansell schreef:
And in these cases, why hasn't wikipedia been completely compatible with CC-BY-SA since its beginning?
Probably because:
[[Wikipedia]]: "Launched in January 2001" [[Creative Commons licenses]]: "released on December 16, 2002"
Except for some very simple ones (such as release to the public domain), licenses are rarely compatible, unless that was a specific aim of the author of one of them.
Eugene