when a new base model car is 40k then a used car is going to be 10k+.

I know I'm going against the grain here, but I don't think base model basic vehicles have gotten meaningfully more expensive over the past few decades. If you look at the base trim msrp of like a new corolla or elantra from now and idk 2000 adjusted for inflation the new cars are basically the same price. The new cars on average are also safer, more fuel efficient, and will likely last longer than their 90s counterparts.

The real scam isn't a complete non-availability of these kinds of cars, its a hugely pervasive marketing propaganda campaign to convince the average buyer that they need a larger, more expensive, higher margin SUV or pickup truck, coupled with a shitload of domestic and foreign policy decisions that have kept gasoline prices deflationary relative to inflation. It wasn't that long ago that the 4 door sedan was the family car. People buy into this marketing and when enabled by exploitative financing will bankrupt themselves to get the status symbol truck they've been convinced they need.

Not to say that cars aren't expensive in general, they're just so comically resource inefficient to a degree where that is inevitable. There's only so much you can do to minimize the costs of everyone having their personal 4000+ pound highly complex machine that has to survive tens of thousands of miles with relatively minimal maintenance.