Where does red pigment in auto paint come from?

Why is red auto paint so expensive? Where does it come from that it is double sometimes triple the price of other colors?Where does red pigment in auto paint come from?
The only answers I found were that red is the hardest pigment to make, whether vehicle paint, actual watercolors, etc, and that it is hard to match red from computer to car. I suppose it is kind of like hair dye -- some fabric/materials just don't allow the red pigment to stick.