“Data transfer prices easily add up, and are an extremely high-margin source of profit for cloud providers”
AWS charges $0.01 per GB in each direction between availability zones, so moving 1TB cost $21.49. Routing the same terabyte through S3 cost about eight cents, because S3 uploads and same-region downloads are free. AWS’s own storage service undercuts its own network pricing by 99%. Cross-AZ fees aren’t physics. They’re a toll.