They have all the primitives. I think it's just that people are looking for a less raw version than AWS. In fact, perhaps many of these users should be using some platform that is on AWS, or if they're just playing around with an EC2 they're probably better off with Digital Ocean or something.
AWS is less like your garage door and more like the components to build an industrial-grade blast-furnace - which has access doors as part of its design. You are expected to put the interlocks in.
Without the analogy, the way you do this on AWS is:
1. Set up an SNS queue
2. Set up AWS budget notifications to post to it
3. Set up a lambda that watches the SNS queue
And then in the lambda you can write your own logic which is smart: shut down all instances except for RDS, allow current S3 data to remain there but set the public bucket to now be private, and so on.
The obvious reason why "stop all spending" is not a good idea is that it would require things like "delete all my S3 data and my RDS snapshots" and so on which perhaps some hobbyist might be happy with but is more likely a footgun for the majority of AWS users.
In the alternative world where the customer's post is "I set up the AWS budget with the stop-all-spending option and it deleted all my data!" you can't really give them back the data. But in this world, you can give them back the money. So this is the safer one than that.