Norberto,
i don't think so

. Wikipedia is absolutely independent, there is no relation between browsers and wikipedia, and that was just an effort to use an independent reference. And its contents is absolutely public, so if it was partial in any way i'm sure it will be objected by the affected part.
The comparision is between used browsers. The version of Chrome never has been significant, but in IE the version means even different products and behavoirs. And, just in case, you can ignore the reference to the other versions and just compare IE9.
May be the fact that previous versions of IE are compared is because there are versions still in use with a strong presence. Even MS is making a campaign in favor of droping down definitively IE6 trying to convince the most resistant users to change.
http://www.ie6countdown.com
In other aspects, the comparisions and test referenced in tables are conducted by internet authoritative entities, like W3C. In any case the sources of every comparision can be traced, and exceptions in the test are observed in footnotes. Interesting independent test to check web standars :
http://www.acidtests.org/
I've been lucky lately, I had the chance to make some experience last years developing internet applications, and the incompatibilities between browsers are a real nightmare. And IE 6 and 7 are the worst, in terms of compatibility with internet standards. Ask to any web developer and probably he/she will confirm my opinion.
Best regards