Regardless of the AWS tech in question (and yes VPCE for non-compute services is a very common pattern in an enterprise setup using AWS since VPC with NAT is a pretty fundamental requirement), I honestly believe this was the biggest miss from the author: “Always validate your assumptions. I thought "EC2 to S3 is free" was enough. I should have tested with a small amount of data and monitored the costs before scaling up to terabytes.” To me this is a symptom of DevOps/infra engineers being too much in love with infra automation without actually testing the full end to end flow.