Why does he, indeed.
We personally know a urologist who performs digital vaginal examinations (DVEs) on all his female patients, regardless of age (and yes, you read that right), on any single consultation. It might be stimulating (in whatever sense) for both parties, but if there’s no medical indication to do this — say, when the patient visits the doctor with complications related to kidney stones, or with a urinary tract infection (UTI) — this is actually not done.
And the man knows this all too well — just like your own doctor.
And don’t even think that your doctor gives his male patients a standard digital as well when they visit him, by the way —