At the price of cars they have to last. If cars only lasted 1 year then they would sell a lot more cars, but they would be all bare bones and lower overall profit - many buyers would be willing to save $500 by not getting the heater option since they have to pay the entire cost of the car every year. Because the average car is 12 years old car manufactures can sell the trade in value of the car - they know someone else will buy the car when it is 3 years old and so the real cost of a brand new car is 1/3 to 1/2 the actually price.
