[zaarn]

In an old project I had 2.8TB of transfer per month between DCs (ie zones in AWS). The hoster provided that service for free, AWS bills this for 20$.

Incoming traffic is charged on a few AWS applications, not EC2, but some do.

That doesn't really change the point though; AWS Networking is magnitudes more expensive than competitors and they bill for things that are accepted as part of the service in other places.