Optimistically, those unplanned outages are software errors, instead of data center management errors. There is an impact to your uptime by using AWS, but it's

Optimistically, those unplanned outages are software errors, instead of data center management errors. There is an impact to your uptime by using AWS, but it's relative to having the same thing runing on not-AWS rather than an absolute value of uptime. The scope of what you can screw up is smaller