You have no idea what you're talking about. Dropping the occasional search result is fine, but what about failing to record billing for the ad system, dropping mails you were supposed to receive in your Gmail account, or failing to save the doc you were editing? Google does a lot more than serve search results, and most of that needs to work every single time.
The fact of the matter is that even the most expensive hardware eventually fails, so your software needs to be able to deal with it and fall back to working units. Once you've written your software to handle hardware failures, you can run on really cheap hardware. And, it turns out that buying a lot of really cheap computers some of which are broken all the time gets you way more computing power than trying to buy a few really robust machines.