Precalculus as a high school senior is supposed to be sufficient prerequisite for calculus as a first semester frosh in college. (This includes Texas A&M’s MATH 171 for physics majors.) Many students do enter college with just precalculus in high school and do fine in calculus in college.
However, there are many high schools with poor quality precalculus courses, so their graduates may not do well enough on math placement exams needed to start in calculus, so those students have to retake precalculus as a remedial course in college.