I often wonder about the implications of having the U.S. government (increasingly) running in Amazon's cloud...
The reality is that AWS is likely not any less secure than legacy IT infrastructure. It also provides great primitives for writing more secure applications.
What does this mean for personal privacy when most of the services you use are backed by one platform?
So yes, much online infrastructure _does_ have AWS dependencies. Sometimes (by way of secondary services) in ways that the operators of the service itself may not be directly aware.