With Craigslist you're generally not looking at a good representation of the "well-equipped or dispositioned" seller; and given the market in the SF Bay area, you're optimizing for one of the highest friction automotive ownership locales in the United States.

If anything you're Also to a degree proving my point on the market at large being skewed toward larger actors; as the capability of the "new entrant" to extract value from the market is significantly diminished. Get that same car to a dealership, and they might even be able to extract even more value for it.

Also, if you're taring the sale at last seller, that's not entirely fair. First sale is what we're discussing, generally represented by first change of hands after factory->reseller.