If you mistakenly spend a small (to AWS) amount of money, they'll refund it. They're not out to get individuals.

AWS is for businesses and hard limits on spending is a liability for their pricing structure. Imagine you run a small business built on AWS and you hit your limit -- you're basically asking AWS to dismantle your business. They'd have to null-route traffic directed to you, shut down your servers, delete your data, de-allocate your IP addresses, etc. Your business won't be any better off than if you went bankrupt from a huge AWS bill.

Or Google. When I was a student I forgot about a TPU instance and spent over $10K in a single month, on track for $100K. Google refunded me since the server was at idle for most of that month outside the one hour I used it for.