Because we were stupid when it comes to the little things, but cars are expensive. And the gov't knows that in a pinch, a car manufacturer can figure out how to make tanks and planes. The last thing we want to do is let unfair competition from China kill off our native manufacturing ability.
Unfair competition due to fewer environmental regulations and fewer labor standards can be remedied by USA creating wage and environmental parity import duties/tariffs. This should apply to everything including iPods and rollerblades.
