It really isn't. FB Marketplace is literally awash in perfectly serviceable vehicles that don't and can't phone home. For the budget conscious among us it's also significantly cheaper to buy a "clapped out" used older car and refresh the drive train than buying new or late model.
Besides the irony of a privacy-conscious user using facebook to buy a car... those "perfectly-serviceable vehicles" are 1. no longer manufactured, and 2. will not last forever.
Unless a new age of unconnected cars becomes a reality in the near future, I don't see this being a long-term solution.
"will not last forever" doesn't comport with observed reality to date. There are literally model A's still on the road. Barring true oddities there doesn't appear to be a model of production vehicle that has gone extinct at any point in automotive history. Anyway, three of my cars are older than I am, and I am not a young man. Buying into their shit is optional.