If you cheat in a professor's class and get caught, and then later, perhaps even much later, after the term in which you cheated is over, you might be out with friends on a Saturday night, having dinner at a restaurant near campus, and then in walks your former professor. You see your former professor, and she sees you. You were laughing at something, but you stop, even though your friends are still laughing at whatever you were all laughing about when your professor walked in. You stay on for another minute or two, but you are so uncomfortable, you get up and leave.
Perhaps you go somewhere else and continue to enjoy your Saturday night, or perhaps your evening is ruined because you are reminded of your cheating, and the F you got on the exam (as a consequence of your cheating), and your interview with some administrators in the office that deals with academic conduct. Perhaps you go back to your room and study or do homework so that you can continue to undo the damage you inflicted on your GPA as a consequence of your cheating.
The professor's evening will not be ruined by your presence in the same restaurant, even though it's not pleasant to be reminded about your cheating. In the rare instances when we professors venture off campus, we sometimes run into students who are happy to see us, we sometimes run into students who are surprised to see us outside of class (but who don't really mind seeing us), and we sometimes run into students who run the other way.
As long as the number of encounters with happy students is > or = to the number of surprised students and >> the number of students who run away at the very sight of us, I am content. It's would also be OK with me if the fear of off-campus encounters with professors served as a deterrent for potential cheaters.
I don't think it likely, however, that anyone who is tempted to cheat will first think "Wait a minute, maybe I shouldn't copy the answers from my friend's test because then the professor might catch me and then I might run into her at that Thai restaurant on X Street some night and have my evening ruined." But perhaps they should.