What many people don't realize is that medicine as a whole is already some sort of expert system (i.e.: a flavor of AI).
There are researchers that conduct experiments to produce meaningful data and extract conclusions from that data. Then there are expert panels that produce guidelines from the results of that research. Most diagnostics and treatments are prescribed following decision diagrams that doctors themselves call... algorithms!
There are several limitations that prevent us from applying other AI techniques to the problem. Off the top of my head:
- We do not have the technology for machines to capture the contextual and communication nuances that doctors pick up on. There can be a world of difference between the exact same statement given by two different patients or even the same patient in two different situations. Likewise, the effect of a doctors' statement can be quite literally the opposite depending on who the patient is and their state of mind. One of the most important aspects of the GP's job is to handle these differences to achieve the best possible outcomes for their patients.
- Society at large is not ready to trust machines to make such intimately relevant decisions. It is not uncommon for patients to hide relevant information from their doctors, and to blatantly ignore the recommendations from them. This would be many times worse if the doctor part wasn't human.
- We cannot apply modern inference techniques (e.g.: deep learning) to the global problem because we have strict rules that prevent medical data collection and analysis without a clear purpose. Furthermore, these techniques tend to produce unexplainable results -which is unacceptable in this field-. As a result, there's not enough political capital to relax those rules.