LLMs are having pretty consistent studies into their biases. Obviously this doesn't mean we know all the biases, but it's being actively worked on.

Meanwhile with human doctors, every one of them is a unique person with a completely different set of biases. In my experience, getting a correct diagnosis or treatment plan often involves trying multiple doctors, because many of them will jump to a common diagnosis even if the symptoms don't line up and the treatment doesn't actually help.