Comment by levocardia

Not even prestigious ones. The school needs to sound like it has strong penalties against cheating, so there are really strict-sounding policies ("zero in the course"). But also, so many students cheat that actually enforcing these policies uniformly would hurt your graduation stats, make unhappy customers (students + parents), and hurt your revenue if you actually expel them. So the equilibrium is that the burden of reporting cheating is foisted upon professors, and it is understood -- though never explicitly communicated -- that academic integrity proceedings will be a huge administrative pain for you, the professor, and it is in your interest not to initiate them.

The outcome is predictable: unless there is a scandal of massive proportions, the issues just..."go away" on their own. With some discretion for the professor to either just look the other way, or ding the student enough to feel vindicated, but not so much as to actually hurt the university's interests.