It's so bizarre there must be some mistake. Does this do significantly more than AWS Cognito which free for the first 50k users? https://aws.amazon.com/cognito/
This price point doesn't make sense outside of the niche SaaS offerings that can charge in the thousands per month.
You're seeing Cognito User Pool pricing. Cognito User Pools is basically having AWS host your user / password / details database for an app you're building. It takes care of some details like verifying e-mail addresses / phone numbers and integrates with Cogito Federated Identities, which makes it easy for your app to (for example) allow login via Google, Facebook, or an account they create (which is stored in that user pool).
This Google service looks more comparable to Okta or auth0. That is like if you're a sysadmin at a big company and you want one place where your users can be authenticated, which can then allow access to all of the web apps you use (Dropbox, Salesforce, Gmail, etc.).
EDIT: And to tie them together a little:
If you were building a web app using Cognito, you could likely add a federated identity via Okta, auth0, or this Google service, which would then allow your users to log in directly to your service through that without having to create / manage an account separately.
> This price point doesn't make sense outside of the niche SaaS offerings that can charge in the thousands per month.
It's not for SaaS offerings at all, it's for organizations like employers, and the purpose is to manage identity for employee devices (including BYOD) and multiple SaaS products (ideally, all of the SaaS products used by the org, though obviously not all existing SaaS offering support it yet.)
This is an upgraded version of the identity management (even for users beyond those with GCP licenses) included with GSuite, though it can be used independently of GSuite.
This price point doesn't make sense outside of the niche SaaS offerings that can charge in the thousands per month.