Unless you are in the UK, you might not be aware that the BBC has no advertisements and it is unable to push any products or services. The reason for this is broadcast laws that go back to the point where the BBC was created.
They had the intention of making sure that they were completely unbiased in any way so it was made illegal for them to have any form of sponsorship. The idea was that the content would be unbiased so you could feel that you were able to trust everything that they were saying or doing in their programs and not wondering if they were going to be putting a certain slant on things just to appease some company that had given them money.
Instead, they are funded by the public paying a fee to have a television or else there is no way that they would be able to run as a corporation due to having no other form of income.