It's not terribly hard to check either. You can do some spot checks with cost dashboards in AWS, Datadog, etc and see if the numbers line up
Can also tell Claude "go right size the environment, pull p95 usage metrics for the last 3 months" and a couple hours later, a bunch of money is saved. Much easier than manually pulling trend data and also easier than installing/configuring/managing tools that do it for you.
The benefits of the time savings of having progressily better tooling over time add up quickly.