“Traditional object storage charges developers for three things: bandwidth, storage size and storage operations.”
S3 charges you to take your own data out. Cloudflare’s pitch is zero egress fees and $0.015 per GB a month, with the S3 API so switching is easy. Egress pricing was never about cost. It was a moat to keep data in AWS. Cloudflare just priced the moat at zero to grab the customers behind it.