- "but there are tons of counterexamples when the teacher/professor doesn't want to deal with the academic integrity process"

That's a good point: in this particular case, the teacher of the course was subpoenaed to federal court and compelled to testify about their grading. Incredible burden, for someone else's problem.

also disciplinary action and very probable expulsion

Last I checked, 65 was a D-, not a C+. So the C+ was for the course.

I have had the rare privilege to see up close examples of how at several US universities, when professors are presented with irrefutable proof that a student has cheated (well beyond any reasonable doubt) the professor will most often do nothing. In the best case they will meet with the student and give them a stern talking to.

The whole system is set up to disincentivize any effort to actually hold students accountable for cheating in a significant way (fail assignment, fail course, expulsion, etc.)

When we read about cases of students being held accountable it's generally the exception not the rule.

Fail to meaningfully discipline students due to fear of litigious moron parents, get sued by litigious moron parents anyway.