<p>From my understanding with giving out retakes, professors tend to rely more on statistical data to adjust for the difficulty of test. In order to do that, there has to be a huge sample size of students taking the test. If you were to have a retake, the professor would have to make another exam JUST FOR YOU. There are two things wrong with that. 1) More effort on the part of the professor and 2) there’s no way for the professor to know if the test he made for you was just as reliable as the test for the entire class with just one data point (your exam). But take this with a grain of salt. This is simply speculation as im only a first semester student. Unlike teachers in high school, professor tend to be more statistical in terms of interpreting test scores.</p>