Which of the following is NOT one of the AWS pricing principles?

Flat rate pricing is not considered one of the AWS pricing principles because AWS promotes a more flexible and usage-based pricing model. The core AWS pricing principles include the concepts of "Pay as you go," which allows customers to pay only for the exact amount of resources they use without upfront payments, making it adaptable for different workloads.

Volume pricing discounts encourage greater usage by providing lower rates as usage increases, thus incentivizing customers to scale their operations on AWS as needed. Reserved Instances are another key principle as they offer significant discounts in exchange for a commitment to use a specific instance type over a specified period. This flexibility and scalability in pricing options are central to AWS’s value proposition, which does not align with the fixed nature of flat rate pricing.