On the other hand, even a little bit off attention of the professors or assistants would expose every last cheater. Cheaters don't even read the assignments they hand in (I've seen people expelled for handing in a paper where the name of the author on the 2nd page onward was different, seen different people hand in the same paper, ...)
A few questions would trivially expose them.
Clearly universities simply don't check. And frankly, we all know that this isn't an individual oversight, but a policy.
But see, I don't think that's "the other hand". It seems unrelated, at best, to the moral question of whether you should profit from helping other people to cheat.
Maybe the schools should put more effort into catching and punishing cheaters. But they shouldn't have to -- if the students were being honest.
The easier and cheaper it is to cheat, the more tempted the students will be. You can lubricate that market by providing the cheating-materials, maybe even by marketing them. Cheating numbers will go up, thus increasing the cost to detect and catch and appropriately deal with cheaters. The last bit is probably the expensive part.
And the more the schools crack down on easily-detectible cheating, the more sophisticated it will get. Sure that means increasing the cost of cheating, but that's an arms race that can only be won by a culture that values honesty. You reinforce that culture by not selling cheating-materials.
This is just the university demanding others do their work for them. Catching cheaters is a part of the service universities provide, and they want to push that cost onto others.
You talk as if cheaters haven't existed before. As if this is new. You cannot prevent this market from existing, the university simply needs to check.
A few questions would trivially expose them.
Clearly universities simply don't check. And frankly, we all know that this isn't an individual oversight, but a policy.