The majority of product manufacturers are not required to provide parts, and apple will fix items under the various warranties it offers. Car manufacturers on the other hand are required to make parts available by law. It is part of the regulation of their industry. They get a lot of protection for their business model, but have some obligations too. It's why the EV1 was pulled, they didn't want to have to make the parts, and why there are so many Delorian parts.