The average car that CARS took in was a 1996 model year with 138,000 miles in 2009. Even if we never did that program they'd be long gone by now.
The current crazy pricing is mostly due to supply that was cut off during covid -- those would all be prime used cars today -- but many were never made, so used car pricing is crazy -- and manufacturers have no incentive to create cheap new cars if buyers don't have other options.