It's not as clear as you think, because companies are watering it down. Just have a look what "serverless"-branded services AWS published the past years.
Take "OpenSearch Serverless" for example: They claim "you only pay for the resources consumed by the workload", but even if you have an OpenSearch Serverless collection you don't use, you pay at least ~$690/month (and that's not even accounting for stored data)!
Take "OpenSearch Serverless" for example: They claim "you only pay for the resources consumed by the workload", but even if you have an OpenSearch Serverless collection you don't use, you pay at least ~$690/month (and that's not even accounting for stored data)!
https://aws.amazon.com/opensearch-service/pricing/