The meritocratic fallacy.
In a meritocracy "merit" is rewarded with success. But we do not know exactly what "merit" or "deserts" means. Does the gifted child deserve to succeed in school? But we quickly agree on what success means, it can be easily measured. So societies tend to infer merit from success, rather than asking in what ways success is deserved. This is also because those who have a lot of success can have more influence on what is recognized as "merit".