Teams typically try to solve cloud spend at the billing layer — reserved capacity, tagging, dashboards. Useful, but downstream of the real cause.
Cost is set by architecture: how data moves between services, how state is stored, how aggressively work is retried, and whether workloads can scale to zero when idle.
Reliability follows the same logic. Systems designed with clear boundaries and observable behaviour are both cheaper and steadier, because the failure modes are known before they occur.