Many trades pay big money just for having the knowledge more than doing work. Being capable =/= Doing lots of work necessarily. I know people being paid big bucks to do nothing until a specific job comes up that requires their niche knowledge. That knowledge can be so hard to find or capable people so sparse that it’s worth paying a lot to have that value on retainer.
Maybe that Dr. Is a specialist? Maybe there’s shortage? There’s plenty of possible reasons, including that person just being a bad worker. Regardless, they definitely spent near a decade to gain enough knowledge and skill to aquire that position. That’s gonna come with a larger salary.