You should call people out for cheating.
Anne is taking a test and notices a fellow student looking at their notes secretly while taking the test.
Anne wants the results of the test to be fair.
Anne goes up and talks to the teacher, pointing out that the other student is looking at their notes.
Anne doesn't say anything and hopes the other student does poorly despite looking at their notes.
The other student receives a 0 on their exam and everyone else in the class gets a fair curve.
The other student gets a good grade and throws off the curve for the rest of the class.