Can't wait for the specific examples
This kind of bias is a statistical measure; typically you can't prove or disprove it using a single sample.
It's about larger patterns, which things are talked about and (crucially) which are not. How much attention is given to things and not.
So many parroting the same "bias" line here, yet not a single example has been linked.
What for? To start a flame war? No one is going to get convinced one way or the other.
Which was why I just wanted to point out that while I think Wikipedia is a net good overall, it is not without blemishes.