I can't tell if your comment is a particularly rude way of picking the nit that "nothing is free, the cost (e.g., of IAM) is built into other services" or if you really find it absurd that the nominal price of many AWS services is $0 or something else entirely.
I apologize for my rudeness. I wasn't adding anything with that comment. I did find the parent comment jarring, as if it was willfully ignoring the downsides in an effort to promote AWS. That's in a comment thread that otherwise seemed like a candid discussion of the pros, the cons, and how it's a good deal for some but a worse deal for others.
Of course, the cost is built into other services. As pointed out, AWS can get very expensive for many use cases, and that's exactly what you're paying for: access to managed services.
Beyond that by developing on AWS you are taking steps to lock yourself into using their system - your configuration isn't portable to other services. So the time/manpower you spend configuring AWS-specific things is another cost associated exclusively with its use.
You don't seem to understand what a 'service' is. In particular, you seem to think a service is something that operates on resources called 'instances'. Here's the Wikipedia definition of a web service:
> a server running on a computer device, listening for requests at a particular port over a network, serving web documents (HTML, JSON, XML, images), which serve in solving specific domain problems over the Web (WWW, Internet, HTTP)
Clearly IAM is a service.
Further, the service needn't operate on resources called "instances" in order to provide value--few AWS services offer "instance" resources and yet they deliver value to customers and are consequently priced. IAM isn't priced directly, but rather the operating cost for the service is built into other AWS services, presumably to encourage people towards security best-practices (charging for IAM might dissuade users from building securely).
