Hah it's always fun when some of the complex trade offs of chip manufacturing spills over to the general public.
People always seem perplexed at first when you ask them if they really thought that anyone can place 15,000,000,000 transistors on millions of chips without any errors. Then you ask what they would do with the "broken" chips and suddenly they understand.
Since most of the transistors go towards cache, what do they do with individual broken cache bits? Obviously they have size variants, but not that many.
People always seem perplexed at first when you ask them if they really thought that anyone can place 15,000,000,000 transistors on millions of chips without any errors. Then you ask what they would do with the "broken" chips and suddenly they understand.