My understanding is that S3 egress is only a problem if you need to take data out of AWS, which you can simply avoid by having some kind of dedicated AWS direct connect or some such to route the traffic yourself?
Connecting to an AWS egress point for direct connect reduces the egress price (about half) but doesn't eliminate it. It also costs thousands of dollars a month just to have the connection, so it's not great for small operations. :-/
If I'm reading the description correctly, egress from there is 2 cents/GB, while the regular price for egress (less than 10 TB) from eu-south-1 is 9 cents/GB.