Judging surgeon competency is much easier than judging physician competency, and physicians make up a much larger share of "medical doctors" than surgeons.

Physicians sometimes jokingly refer to surgeons as "technicians" because what they are doing is often more discretely defined, clearer boundary conditions, clearer indicators of performance/success/quality (especially over X number of cases when you know the national averages for outcomes), and ultimately of a mechanical nature. The work physicians do can sometimes be described similarly, but much less frequently and it can be much harder to do.

The physician/surgeon distinction is a critical one in medicine that is under-appreciated in most conversations about "doctors".