"When deploying infrastructure across multiple AWS availability zones (AZs), bandwidth costs can become a significant operational expense"
An expense in the age of 100gbit networking that is entirely because AWS can get away with charging the suckers, um, customers for it
reduce network bandwidth from the network attaches SSD volumes, yes?
AZs are whole datacenters, so I imagine their backbone bandwidth between AZs is a fraction of total bandwidth inside the DC. If they didn't charge it'd probably get saturated and then there's not much point in using them for reliability.
The internet egress price is where they're bastards.