They surely took the SAT, and they may have been hooked (athlete, URM, etc). You will be competing against international students with the full package of top qualifications. A student with perfect SATs and perfect grades and amazing recs and supurb ECs might get accepted without the subject test scores. But weakness anywhere and no subject test scores will result in moving down the list of who they want to admit. It is holistic to a point – but the student with a great app who also did well on the recommended items has an edge.