You must remember that "Expert System" is a term used in machine learning which specifically means a system in which the input is (logically, not literally) pro

You must remember that "Expert System" is a term used in machine learning which specifically means a system in which the input is (logically, not literally) processed by humans at every step until the output is provided, rather than a term to describe "the best" AI systems. As mentioned in the quote, this is usually done though if/else "if this is the case, then the next step is that". The reason they are called Expert Systems is that they provably provide the correct output for any input 100% of the time.