Nobody calls Newt Gingrich "doctor" and he was a college professor with a history Ph.D. https://twitter.com/NathanWurtzel/status/1338184883785641986
Jill Biden has the same degree as Bill Cosby.
Ron Paul is often not referred to as "Doctor" in media reports, and he was an Air Force surgeon & practicing OB/GYN. eg, the NY Times calls him "Mr. Paul": https://www.nytimes.com/2020/09/25/us/politics/ron-paul-hospital.html
Rand Paul graduated from Duke Medical School and has an M.D. & a Kentucky medical license, but nobody calls him "Doctor."
Again, media reports rarely refer to Condoleezza Rice as "Doctor" even though she has a Ph.D. in political science, was Provost of Stanford University, & has spent most of the past four decades in academia.
How often did you hear Charles Krauthammer or Michael Crichton, both graduates of Harvard Medical School, referred to as "doctor"?
Lynne Cheney is another excellent example. https://twitter.com/JonahDispatch/status/1338281401804869635
Ben Sasse has a Ph.D from Yale and was a university president. Nobody calls him Doctor. https://twitter.com/AdrienneRoyer/status/1338283508968665088
Him too - and he's an extensively publshed author in the classics, the area of his Ph.D https://twitter.com/HKirsh1/status/1338283719174606848
I'm quite sure I have never heard anyone call George Will "Doctor" https://twitter.com/rkylesmith/status/1338283849319669763
More examples of people with doctorates who were rarely referred to as "Doctor" in public https://twitter.com/AdrienneRoyer/status/1338285041147895809
Meanwhile, roughly 99% of the people who are gung-ho for "Dr. Jill Biden" will laugh in your face if you offer a word of respect for the credentials of Dr. Ben Carson, an actual renowned Yale-educated brain surgeon.