“Anyone who refuses gets the side of his car keyed with the metal frame of the squeegee.”
That’s a new one to me. The ones I’ve seen (admittedly only a couple in my life), threw their bucket of filthy water on the windshield if they didn’t get some spare change. Nasty, but less serious than a key job.
As for the prof’s argument - bleah. So much nonsense in that notion (they only do it to earn a living), I wouldn’t know where to begin.
Used to see this in France a lot. Same thing but little Algerian kids then.
The problem is the prof’s thinking, and that he is a prof.