At a more selective college, the students were A students in high school. But some will be B or C students in college.
Is this about the courses (which may seem difficult to students making the adjustment to college, or because the courses have to cover material rigorously enough because they are important prerequisites to later courses), or does this college have more demand for majors like business and engineering than it has space for, so it imposes a high GPA requirement or competitive admission to get into those majors? Some colleges which have oversubscribed majors do not admit directly to the major, but have entering students compete by college GPA (and sometimes additional criteria) to get into the major. This can create a “weed out” environment, regardless of the difficulty of the courses.