Physics: Cars are often made with higher cost disk breaks?

Question

Cars are often made with higher cost disk brakes on the front wheels and less durable drum brakes on the back wheels because there is greater force on the front brakes when stopping. With reference to physics principles, explain why.

Answer 1

Here's my theory:
The front wheels bear more weight per wheel because the engine (very heavy) is almost directly above them. The back of the car tends to be lighter. Because the front wheels have more downward force on them, they have more friction with the surface (or traction in automotive terms), and thus exert more of the braking force.

If I remember correctly, the force of friction is equal to the coefficient of friction times the force in the direction perpendicular to the surface.
In the case of a car, the coefficient of friction is determined by the road surface and the tire characteristics, and is generally equal on all tires.
The perpendicular force in this case is the weight carried by the specific tire. As I said, the front tires bear more of the total weight. The sum of the weight on the four tires is equal to the total weight of the car. (This includes the fuel in the tank, the passengers and the cargo.)