I was actually thinking about OBD2 when I wrote that. The old CRT pedestal style code readers cost as much as a new car, fairly reasonable from an automakers perspective but expensive enough to put plenty of small shops out of business.

It was one of the first big top-down push that I remember. It’s a pretty good parallel for the current right to repair legislation. The automakers fought it tooth and nail back then too. They made similar claims about their new cars being so complex that they simply had to be serviced at the dealerships. And, to your point, they are still getting away with it to a degree.