I didn't cheat because it repelled my moral code, and my suspicion that others were cheating added to my stress. A morally-grey friend said there wasn't any moral problem with cheating, but I don't think he did because there wasn't a point (in his view). He would later TA a class and caught some cheaters, whom he reported.
Perhaps "high standards" wasn't the correct choice of words on my part. I meant they all except themselves to get good grades. In particular where I went, where the school is largely populated with pre-meds where GPA is everything! If they're in a situation where the reward for cheating is high and the likelyhood for getting caught is low and they don't see any other option (not that there isn't but often they don't see it) they are likely to succumb.