Heavily contrasted things such as a janitor and a surgeon are not what is meant a meritocracy. What is usually meant is within an organization of surgeons ranked based on talent, effort, and achievement. Fact is all of those things are based on politics, perceptions, and in some cases luck -- especially the higher up the hierarchy you go as individuals may get credit for efforts of people below them and all of that is attributed to their efforts.

The most competent surgeon may seem the most competent because she only takes easier cases. A good surgeon might work 36 which might be worse for his patients survival than if he works 12 hour shifts. You might get individual surgeons that are very lucky in terms of their success rate, not for any other reason than survivor bias. You might get a team of surgeons where a leader takes credit but it's the juniors that are actually really good at what they do.