Google is the leader in large scale infrastructure for a single (or small set) of customers (Google, Youtube etc). You could call this "private hyper-scale cloud". AWS is the leader in vending that infrastructure to the rest of the world (a.k.a. public cloud).
I would argue that over time the second market will be much larger and more important than what Google built internally.
> a single (or small set) of customers (Google, Youtube etc)
Well, the applications inside Google are equally diverse compared to applications running on AWS, or at least on the same level. Google's infrastructure is used for an extremely wide range of use cases, from running a shell command remotely, to support planetary deployment of world's largest customer-facing applications.
It was not designed for simple or uniform use cases. Actually, it is impossible to design something that is simple and uniform, and at the same can support Google's growth on the way.
Your examples, Google (search), youtube, are actually examples that have extremely diverse requirements across their entirely tech stack. In fact, many of its requirements cannot be supported in any existing public Cloud providers.
Though, to be fair, Google is investing a lot in exposing some of its internal infrastructure as a public cloud. It's a relatively late comer to that game, but that game is also just getting started.
I would argue that over time the second market will be much larger and more important than what Google built internally.