playing the piano well also requires practice, discipline, and effort. it's not science. it's an artistic performance skill.
meditation is an empirical approach to psychological and spiritual development. there is a lot of overlap between the empirical approach of Buddhist meditation and the empirical approach of Western experimental science. however, it's not accurate to describe meditation as science.
I believe mediation is science, since it requires practice, discipline and effort. Some might not see results immediately, but keep pushing.