If you ask ChatGPT to cite it will provide random citations. That's different from actually training a model to cite (e.g. use supervised finetuning on citations with human raters checking whether sources match, which would also allow you to verify how accurately a model cites). This is something OpenAI could do, it just doesn't.

We recently improved source links in ChatGPT(opens in a new window) to give users better context and web publishers new ways to connect with our audiences. 

AIs are not capable of citing the sources of knowledge used up to the standards of the Stack Exchange network. Even when Artificial Intelligence appears to cite sources for responses, such sources may not be relevant to the original request, or may not exist at all. For Stack Overflow, this means the answer may not honestly or fairly represent the sources of knowledge used, even if someone explicitly cites the Artificial Intelligence as an author in their answer.

he had used ChatGPT to conduct legal research for the court filing that referenced the cases and that the artificial intelligence tool assured him the cases were real.