I do believe that Wikipedia is one of the least biased sources out there, but there is definitely bias. Here is a concrete example. Compare the introduction paragraph of the English circumcision article ( https://en.wikipedia.org/wiki/Circumcision ) with the German one ( https://de.wikipedia.org/wiki/Zirkumzision ). The English intro talks a lot about medical advantages of the procedure: "reduced rates of sexually tr…
I think this is the wrong way to look at bias. Bias isnt a binary, instead its a journey to try and get succesively less and less biased. You can never achieve absolute unbiasedness, you can just try to journey closer.
And yes, wikipedia is far from perfect.