The BBC is a flawed institution, but it is not in the thrall of advertisers, like all the other channels. As globalisation means that there are a few big companies who own huge numbers of small ones it can be extremely difficult to have unbiased reporting. An expose of, say, a drug that harms unborn babies may mean that all advertising from any of the companies under the same umbrella is pulled, and that could be for teabags, face cream, breakfast cereal or whatever, and be ruinous for the channels.
The BBC may have government interference, which it shouldn't, but it is not working under the constraints that commercial channels have to consider.