I think you also ignore the chilling effect this had on the class itself. It's quite possible that the students who did not cheat experienced a worse class because of the change in atmosphere.
Setting the expectation for academic honesty in the syllabus and directing students to university policies is more than enough. In any event, it should just be handled privately. There's no reason to jump up and down and hold your breath in front of the class.
Regarding your second point, if any one thing becomes a trend in a class, you bring it up with the class.
As for your second point, preaching to the choir is a waste of time and just makes them uncomfortable (as this case points out), the come to Jesus talk is a one on one affair.
There's also the aspect of a student being falsely accused of cheating. I was unfortunate enough to have experienced this during my college career. A fellow student, whom I didn't know outside of class, copied my answers exactly on a German exam. I don't know why he did this, because there were only 15 students in the class and the professor knew us all fairly well. To think the professor wasn't going to notice was a stupid assumption on his part.
I was called in to her office and shown the two tests. The answers were the same down to the punctuation even. It was clear the other guy was very bad at cheating and probably did it out of desperation. I was initially shocked and feared I was going to fail the class despite my innocence. She had to refer the incident to the honor board due to university policy. When I left her office I was so furious that I looked up where the other student lived because I wanted to fight him. But I took a walk, cooled off and decided against it.
I was ultimately cleared by the board and there were no marks on my record. After the proceedings were over, the professor apologized to me and said that she never believed for a moment that I had cheated, or that I had helped him cheat. She pleaded with dean to avoid sending the matter to the honor board, but she had to follow policy.
She said she never had any cheating incidents in the past, and that it was personally distressing for her to handle the situation. It was definitely stressful for me as well.
To put it another way, a professor should focus on teaching and let those tasked with investigating cheating and listening to excuses sort it out.
And yes it can and should be as impersonal as a parking ticket. Cheating is a simple violation, and it behooves a teacher to forgo emotional investment in each case. Avoiding interrogations and Perry Masonesque cross-examinations would seem like a good way to avoid such an investment. When 1:5 students in a 100 person course is doing so, reporting cheating is a purely administrative matter of the same sort as turning in low grades for poor students - which hopefully is something the author still does not find to be too much bother.
A Turnitin report as cited in the article would be about as much evidence as would be needed. Particularly when Turnitin is the institution's official means for combating plagiarism...not to mention the level of matches described in the article would make it appear open and shut.
Yes, it might require some involvement from the professor - but the implications of complaining that such involvement is too much work is the basis of my criticism of the author's position.
[1] - If your method is 99.9% accurate, you've got a 50% chance of a false positive after 700 submissions, which for a 100 person class is a milestone you could hit in your second semester.
By your logic, one could make the case that academic standards should never be upheld - 700 submissions is arbitrary and could just as easily be 7000 or 7,000,000 and the same rationale would apply.
So at best, you're looking at 10% unpaid overtime for a job that already requires a lot (maybe up to 100%) unpaid overtime.
FYI, I get paid to teach 17-20 hours a week, but with prep time and marking it ends up taking about 30-40 hours a week.