Left out of this discussion is that Amazon sells various tiers of service that, roughly speaking, correspond to level of problems your application will survive. That is, if you want a service that can survive the loss of one data center and failover to another, you can buy that from Amazon. The companies that lost service when Amazon's backup power didn't come on didn't buy that level of service. They made a bet on costs and seemingly lost. But if they don't actually lose customers/revenue, then they haven't really lost. They've proven that services like theirs can go offline for awhile and not effect their business prospects.