There's very real differences between NAT gateways and VPC Gateway Endpoints.

NAT gateways are not purely hands-off, you can attach additional IP addresses to NAT gateways to help them scale to supporting more instances behind the NAT gateway, which is a fundamental part of how NAT gateways work in network architectures, because of the limit on the number of ports that can be opened through a single IP address. When you use a VPC Gateway Endpoint then it doesn't use up ports or IP addresses attached to a NAT gateway at all. And what about metering? If you pay per GB for traffic passing through the NAT gateway, but I guess not for traffic to an implicit built-in S3 gateway, so do you expect AWS to show you different meters for billed and not-billed traffic, but performance still depends on the sum total of the traffic (S3 and Internet egress) passing through it? How is that not confusing?

It's also besides the point that not all NAT gateways are used for Internet egress, indeed there are many enterprise networks where there are nested layers of private networks where NAT gateways help deal with overlapping private IP CIDR ranges. In such cases, having some kind of implicit built-in S3 gateway violates assumptions about how network traffic is controlled and routed, since the assumption is for the traffic to be completely private. So even if it was supported, it would need to be disabled by default (for secure defaults), and you're right back at the equivalent situation you have today, where the VPC Gateway Endpoint is a separate resource to be configured.

Not to mention that VPC Gateway Endpoints allow you to define policy on the gateway describing what may pass through, e.g. permitting read-only traffic through the endpoint but not writes. Not sure how you expect that to work with NAT gateways. This is something that AWS and Azure have very similar implementatoons for that work really well, whereas GCP only permits configuring such controls at the Organization level (!)

They are just completely different networking tools for completely different purposes. I expect closed-by-default secure defaults. I expect AWS to expose the power of different networking implements to me because these are low-level building blocks. Because they are low-level building blocks, I expect for there to be footguns and for the user to be held responsible for correct configuration.

AWS VPCs are secure by default, which means no traffic traverses their boundaries unless you intentionally enable it.

There are many IaC libraries, including the standard CloudFormation VPC template and CDK VPC class, that can create them automatically if you so choose. I suspect the same is also true of commonly-used Terraform templates.

As others have pointed out, this is by design. If VPCs have access to AWS resources (such as S3, DynamoDB, etc), an otherwise locked down VPC can still have data leaks to those services, including to other AWS accounts.

It's a convenience VS security argument, though the documentation could be better (including via AWS recommended settings if it sees you using S3).

I've been testing our PrivateLink connectivity at work in the past few weeks. This means I've been creating and destroying a bunch of VPCs to test the functionality. The flow in the AWS console when you select the "VPC and more" wizard does have an S3 Gateway enabled by default

If it were opt-out someone would accidentally leave it on and eventually realize that entire systems had been accidentally "backed up" and exfiltrated to S3.

AWS VPCs are secure by default, which means no traffic traverses their boundaries unless you intentionally enable it.

And ECR, which I would guess impacts more folks than DynamoDB https://docs.aws.amazon.com/AmazonECR/latest/userguide/vpc-e...

And, as as added benefit, they distinguish between "just pull" and "pull and push" which is nice

True, I forgot that. But depending on services you still have to have some Gateway and some Interface endpoints.

Why don't you have gateway endpoints for all your APIs?

It's more like: we made loads of stuff super cheap but here's where we make some money because it scales with use.

Price segmentation happens all the time in pretty much every industry.

That's fascinating! I hadn't found that in the documentation; everything seems to steer people towards PrivateLink, not gateway endpoints.

Would you recommend using VPC Gateway even on a public VPC that has an Internet gateway (note: not a NAT gateway)? Or only on a private VPC or one with a NAT gateway?

Fair point, and valid for S3 (the topic at hand) and DynamoDB.

Other AWS services, though, don't support gateway endpoints.

I doubt the traffic ever actually leaves AWS. Assuming it does make it all the way out to their edge routers, the destination ASN will still be one of their own. Not that the pricing will reflect this, of course.

The other problem with (interface) VPC endpoints is that they eat up IP addresses. Every service/region permutation needs a separate IP address drawn from your subnets. Immaterial if you're using IPv6, but can be quite limiting if you're using IPv4.