There are per-API-call charges. It's just not per-byte.
(WarpStream founder) Exactly, and we designed WarpStream's storage system to minimize the number of object storage API calls it has to make while still maintaining relatively low latency (P99 of ~1s end-to-end)
S3 requests are paid regardless of source (tldr GETs are cheaper than PUTs). You're confused with data transfer within a VPC.