I'll retreat to saying that claims about the superiority of Google's code writing process remain unsubstantiated.
During my 3 years at Google, I observed little brilliance. Not that my little corner of the giant org is a statistically valid sample.
I did see a fair amount of "Google is The Best!" sentiments and rejection of anything invented outside the company.
- The risk aversion to anything that threatens a big existing successful product.
- The product/feature approval processes that implements the above.
- The concern about launching something experimental or half-baked under the brand (vs a startup which does that by default).
Personally, I saw a lot of product and engineering creativity, but it was often stifled or watered down by the above.
This is a very simplistic notion of what enables the creation of killer products. That has much more to do with understanding users' needs and identifying market opportunities. Good code writing processes are about code maintenance and scaling engineering effort, not dreaming up the next killer app.