Because, at least in my opinion, doctors should be considering base rates carefully. If I come in with an unusual set of symptoms, then I don't want to be tested for something that is vanishingly unlikely and not tested for something that has an unusually high frequency of occurring given my specific situation (demographic, race, vaccination rates in the community I live in for diseases that can produce my symptoms, etc.)
Medicine should not be one size fits all when better relevant data are available.
Different but related: I personally use similar information to determine the risk of various behaviors. Going to a meeting in someone's house where people won't be masked? Not a big deal if the current rate of community infection is very low in my local community. Playdate for my kids with friends who I know are not vaccinated for measles or pertussis or anything else? Depends on whether those are going around—and if they are, then I'd like to know how many kids are unvaccinated whether or not they're lying about it. If there's a way to get that aggregate information.
Running with the 12% figure, I'm still curious as to how that is useful. Have you traveled recently? Been to a large gathering? Never left your house? Visited with family from out of town? Do you commute for work as a front-line worker?
Risk profiles for less common diseases make sense, but these are questions your doctor should ask regardless of the infection rate of your zip code in a pandemic scenario, however.
> Medicine should not be one size fits all
I don't think it's unreasonable to expect tests for most obvious fit of your symptoms (with followups for less likely causes if those are negative) rather than needing to do statistics puzzles for every patient that comes in through the door.
I am asking this out of genuine curiosity: Why? What actionable information does that tell your doctor about you, specifically?