These seem largely to be straw-men; brake rotors, pads, headlights.... all have associated safety standards. You can install your own brake pads sure, but as a

These seem largely to be straw-men; brake rotors, pads, headlights.... all have associated safety standards. You can install your own brake pads sure, but as a layman if you installed brake pads of your own design and construction, it might be a bit of an issue.