If you don't want to bankrupt yourself then check your usage every day or hour. It's still your responsibility not your vendor's.
It's like saying "this website is stupid, it's storing passwords in plaintext", and you answering "hurr, it's the user's responsibility to create and manage cryptographically secure passwords".
And as an analogy, Aws is more like C; if you are willing to put the time in to learn, you can do some amazing things that are impossible with other providers. But you must take responsibility for them.
I'd love to hear use cases where legitimate businesses, who make money off of the products or services they offer, can literally afford to have their business just stop working. It sounds totally contrived.
In fact, we use an SNS->Slack gateway running on a free Heroku dyno to get out alerts in a Slack channel (which is pushed to phones/etc), along with other CloudWatch alarms related to performance.
Honestly, this issue of "I don't have any visibility into what I'm spending" is a waste of energy. You do, and you can have AWS bug you as intensely as you want with updates as frequent and as urgent as you need