For enough time and money dumped into code auditing and hiring smart people, no. Not that most companies should do that, but it is possible if you want to pay for it. Most companies (rightly) prioritize innovation, scalability and profit margins over absolute reliability.
How many of those top sites actually prioritized reliability? Is it even justifiable for their business models? I bet you can find a lot better reliability engineering in bank, credit, and stock systems. For example, when was the last time the Visa credit network crashed (as a whole, not localized outages)? Nasdaq?
See the linked discussion, only 3 out of 20 top sites had 5 nines.