It is not an anomaly, it is simply that an mD and PhD requires you more likely to actually be smart,or you would not get certain phDs ever. 76% of PhD recipients are not hesitant as you can see, so 3 out of 4 are still dumb
Degrees have been watered down over the years. It would seem the genuinely smart are refusing and the token "I am very smart" crowd are following the herd as usual.