Solving this for any one resource type, or one billing axis, is absolutely achievable in the ways you've suggested. Solving this across all resource types and

Solving this for any one resource type, or one billing axis, is absolutely achievable in the ways you've suggested. Solving this across all resource types and billing axes however is a different problem. You can't cache the notion than a VM is under the billing cap for an hour if there's another service that push spend over the cap within that hour. You're right that you could establish SLOs across everything and minimise the amount of monetary loss, in theory, but at scale (as some resource types necessarily bill infrequently, as customers are spending more per hour), I suspect even this breaks down. Then there's still the issue of billing at rest. Do you shut off VMs? That might be an easy question to answer. Do you delete their storage though? Harder. Do you delete blob storage? Probably not, but you've got to swallow the cost of that until the customer decides to pay again.