Let's see if college admissions are, at least in part, meritocratic. College admissions depends highly on SAT scores and GPAs, these are probably one of the two strongest factors. Even just spending 20 hours following along with free videos is associated with a >100 point gain on SAT scores [1]. Spending more time on studying does increase grades on average [2]. Test scores and grades are some of the primary factors that determine, for example, college admissions. So, yes there is empirical evidence to suggest that college admissions do depend on several meritocratic factors. Granted you're right that it's not completely a meritocracy. Factors outside of the applicant's control like race, gender, and family background are taken into account. An Asian student and a Black student are going to be judged very differently if they have the same scores - that is at least one instance where the system is not genuine meritocracy.
1. https://www.washingtonpost.com/news/answer-sheet/wp/2017/05/...
2. https://news.osu.edu/the-secret-to-academic-success-hours---...