This is mainly because you only pay for the partial value of the car and not its market value as a whole.
It is your responsibility as the purchase of the buyer who used the car to see the reserved price.
Most of the guarantees provided by these retailers are limited in nature and provide a much lower coverage.
Auto extended warranties protect you from inflation later when you need repairs.
The corrosion or rust warranty protects you from the car metal corrosion hassle.
They often underestimate the cost of vehicle repairs and think that the manufacturer's warranty is more than sufficient.