Because neither the BBC and VOA are produced by the publicity arm of a particular British or American political party.
(“But”, you say, “the PRC is structured as a one party state, so there is no difference between party media and state media.” And that's true, but not in a way which elevates the credibility of party organs, just one that degrades that of state organs compared to ones in regimes where state institutions have some institutional protection against partisan patronage. Which is not to say that state institutions are ever neutral sources on the interests of their own state, just that even among structurally biased sources there are still different levels of unreliability.)
I don't know the internal of VOA or BBC or China Daily. I think you agree there may be bias in each media. When we analyze data with extreme values via programs, we use mean or median values and get rid of the extreme values. I think the genocide accusations are some extreme values and I don't trust them. I just post the different sources with different views on the topic. One of the source is from China Daily, and the other source is from a French author. I think hearing from different sources make us have a clearer view on the topic.
(“But”, you say, “the PRC is structured as a one party state, so there is no difference between party media and state media.” And that's true, but not in a way which elevates the credibility of party organs, just one that degrades that of state organs compared to ones in regimes where state institutions have some institutional protection against partisan patronage. Which is not to say that state institutions are ever neutral sources on the interests of their own state, just that even among structurally biased sources there are still different levels of unreliability.)