My basis for this assertion is that I know very few people who are duped into buying maintenance contracts. Those things aren't "included in the purchase price" for anything but the highest end of mass market cars, they're overpriced tack-ons that dealerships push hard when you're purchasing a car.

Granted, I know very few new BMW owners (and the few that I do know, know very little about cars and just wanna go fast); most everyone I know who has a US- or Japan-make car doesn't bother with going back to the dealership, and that's the vast majority of car owners in the US.

EDIT: The other thing to keep in mind is, most Americans aren't buying new cars. In our tech centric bubble, sure, nearly everyone buys a car new off the lot, but in my sample size of a few dozen people in Ohio who are almost all professionals working decent office jobs, maybe half my friends have ever bought a new car, and the rest are driving something second hand. And keep in mind, these are young professionals with low debt and decent financial sense. The average person in the US almost certainly can't afford a brand new car on a frequent basis, and certainly not the dealer markup on services.