When I bought my Prius, I was looking at 1-3 year old used models that were only about $3-5k less than a new one, and came with a worse warranty. The two years of free maintenance that came standard with the new Prius covered a significant part of the price gap, and the new one had more life left than the used ones, which I think covers the other part of the gap.
On the other hand, it rarely makes sense to buy a new Chevrolet or Ford, or Mercedes, for example. The resale value on those is terrible.
It seems that he was partly inspired to write this by "the TTAC reader whose response to Bark’s article on subprime buyers was to straight-facedly suggest that a working father swap his own minivan transmission in his apartment parking lot."
I used to own beater cars when I was in college and shortly after. I never paid more than $3k for one, and I did all of my own work, including replacing all of the brakes on one of the cars myself. But I like working on things, I already owned the tools, and I had access to good public transit when my car broke down. I would not recommend beater cars to most normal people.
Buying non-luxury cars is NOT expensive. Throwing away a working car is expensive.