@md-2020 does your school have a ban on cellphones or search students before entering tests or require all professors to forbid restroom trips? Do people with ties to frats/sports teams/other groups not get access to prior years' exams that are unavailable to the typical student? Are there no assignments to be completed at home which could be readily plagiarized or ghostwritten? Are there no problems sets intended for individuals which people trade their answers and scores on (eg I answered b,b,c,d,a and got 4/5)? Are there no assigned problems/homework from textbooks, such that torrenting the teacher's edition with full solutions provides an advantage? Etc, etc.
I have certainly had classes that were very cheat-resistant, but being unethical/dishonest can give you a solid advantage in many classes, especially if you have friends/students from prior years to help you.