And then attaching a user interface to the data that guides the user through a step-by-step self-diagnose process.
There are also a lot of rare things that need expensive procedures that shouldn't be done on a whim. Many medical tests increase your odds of cancer for instance - if you really need that test done to figure out your issue it is worth it, but those tests shouldn't just be done - it is often better to treat the most common causes without verifying that is really the root cause and then only if those treatments fail do the tests to see what you really have.