I think the issue is one of data gathering and input. With a patient presenting with a possible infection, who's going to ask the questions to determine the right antibiotics or tests to order (also not forgetting that this patient might not have an infection, I'm not sure in what setting you imagine such an already differentiated patient arrives)? If you've interviewed patients then you know there's a lot of noise to shift through. And who's going to do the physical exam?
With radiology, we're just focusing on the image which is already in the computer anyway.