They are for the same reason. How do customers react to either? If us-east-1 fails, nobody complains. If Microsoft uses a browser to render components on Windows and eats all of your RAM, nobody complains.
Oh, people complain. The companies responsible have just gotten to the point where they are so entrenched that they don't need to care at all about customer complaints.
Oh, people complain. The companies responsible have just gotten to the point where they are so entrenched that they don't need to care at all about customer complaints.