> There are 100s of AWS services and many where you can't just apply a sensible rejection policy once you hit that hard limit without doing something the user cannot recover from. It's only not hard because you aren't actually thinking about the matrix of AWS products that exist and how they are billed.

I don't think you understand what a hard limit is. When I set a hard limit, that means that under no circumstance should I be billed more than this amount. From this you should be able to deduce that the platform needs to stop you from ever entering into a situation where they could end up having to decide between nuking your data, or overcharging you.

This means that for all data storage scenarios, they should apply limits to projected monthly usage rather than actual monthly usage.

If 1 GB of storage costs $1 per month, and my monthly limit is set to $10, then they should not allow me store more than 10GB of data, rejecting writes as needed. This design guarantees that my hard limit won't be exceeded and the data is never at risk.

Any service which doesn't persist data can apply limits based on actual usage, and safely shut them down when the limit is exceeded.

> Does Amazon drop your entire database once the credit limit is reached?

No, they should refuse further writes when your database reaches a size that would exceed $10 a month. That's a safe behavior.

> Consider secret manager. You are charged 40 cents/month per secret. You have 100 secrets, so $40/mo, but you set your hard limit to $20.

If you set your hard limit to $20, then Amazon should refuse to create more than 50 secrets. That's a safe behavior which limits your spend to at most $20.

> Building all this out just so that some college kid isn't charged a bill they could obviously never pay likely isn't a good use of resources. It's not likely AWS has a reputation of being greedy either, if you explain the situation they refund you. If they are truly doing this to make money they have remarkably poor execution.

This is just a bad faith argument, everyone from broke college students to medium sized businesses has complained about this at one point or another. Relying on the good will of a megacorporation to forgive a surprise $100k bill is nuts and if you scroll through these comments you'll find some that claim that AWS is no longer forgiving these bills like they used to.

I'm not claiming that this solution is perfect, or that it would cover every failure mode, but it sure beats the status quo and would solve the vast majority of surprise bills that result from unexpected traffic.