That's incorrect, at the Daily Show they have a large fact checking team because they want their jokes to be based in fact. The Daily Show has also done apologies and retractions when they were incorrect. It is a comedy show but they are working hard to be correct, there's a great episode of NPR's Fresh Air where they speak with a Daily Show producer about exactly this issue.

Edit: I have heard Stewart say "we're not the news" in response to questions like "Do you feel a responsibility to cover every important issue?" where "we're not the news" means they only cover issues they can make funny (an example of something perhaps too sad to make funny is the Flint water crisis)