Because Apple displays the processes to signal the build quality. And some build processes that enable them to use special materials - which doesn't imply that the materials are superior.
It's well known that Apple's laptop LCDs are average at best. I can only assume their PCBs are produced on the same equipment their foxconn et all use for their other customers.
Still, the aluminium bodies are nice, but maybe other materials would be better (Magnesium)? The MacBooks are quite heavy, for example.
Granted, there is a lot of trash computers out there, atm I don't even know which ones would be nicer than Apple's (since Samsung has screwed up the design lately). But I haven't done the research, either.