You can set up billing alerts to trigger actions that stop things when they trigger. The easiest way is to take permissions away from the roles you create.
They give you the tools. It’s up to you to use them. If that’s too difficult, use the AWS LightSail services where you are charged a fixed price and you don’t have to worry about overages or the new free tier
Because despite what everyone here is saying, before July of this year, there was no such thing as a free tier of AWS, there was a free tier of some of their services
Instead of lightsail, I'll use digital ocean. It's a cheaper way to get undifferentiated VMs.
If it is so easy to set up these automations, Amazon can easily set up this automation for you. Ask yourself why they don't.
$1 cheaper per month for the lowest performance VM on both?