Here is my take: too many people go to college these days because they need the validation of the degree, not because they are interested in learning anything. Because a college degree now is what a high school diploma was a generation or two ago (in terms of job requirements), there are plenty of motivated people who just want to get through their classes so they can get a decent job with some security. The system doesn't care if they have any particular knowledge, just if they have a degree. This encourages gaming the system, so it is only natural that some people make a living serving that niche.
I don't work too hard to catch cheaters myself. I follow all the security rules set up by my University, I don't put too much weight on things that are easy to fake (like online quizzes), and I give out old reference exams to level the playing field a bit so students don't feel like they need to buy copies of my old exams. Anything obvious I crack down on, since otherwise it can be very demoralizing for my hard working students, but I have too much to do to try to worry about all the ways a student can cheat on an exam.
That said, I don't collect my assigned problem sets, because I am not a jailer keeping my students from free time. The ones that want to learn do the assigned work and learn. The ones that don't, don't. I tell my students that they will get out of my course what they put into it, and I focus on the ones who are trying to learn, not the ones who are gaming the system. There will always be cheaters, and people will always try to game the system. Many of the rules designed to catch cheaters make life much more difficult for everyone.
I still believe that the cream will rise. I have a hard time thinking that someone who pays ringers to do all of their work for them will be able to pass an oral board exam in medicine, or stay on the job for very long as an engineer, or make it as a bench scientist, making their "fake" credential a very expensive gold star. If someone can learn the material without doing the assigned work, that means they have talent, and I wouldn't mind working with them if their "fake" degree gets them in the door. The bigger problem in my mind is the disconnect between the credential and the competence of the credential-holder. We see academics complain about this all the time when recruiting postdocs. It seems just as true in every other field. Buying papers is just a symptom.