It's worth asking "Compared to what?"

Unless my memories of their business model are incorrect, you pay a subscription fee for access to their stuff. Same as their competitors; in the case of the one I know best, the DirectTV my parents use, heavy rain knocks out their K band based transmission systems. Cable companies are also known for providing something less that 5 9s uptime.

Netfilix might be quite willing to accept these occasional outages for what else they perceive AWS proving them.