The saying at my kids college/university was “A ‘C’ gets a degree”. And while “haha that’s funny” there were many in that group that took that literally and put in the least effort possible.

I've been in classes when I could ace the class in my sleep and classes where I busted ass to pass.

Grades tend to be highly subjective, not just by subject or material but by the course instructor and the school's attitude towards GPA. Sort of a joke that getting an "A" in colleges like Harvard and Yale is easier than Boston College or Ruetgers. You're de facto assumed smart if you're in the Ivy League. But you have to prove yourself against the field in these more accessible schools.