It really feels like they design the thing to make that happen.
I got stung for over $100 just as a casual user, because I never guessed that I had to click through all the (slow loading) regions to see the instances and volumes and snapshots I might have burning money.
That was a concern of mine until I created alerts. Now I get emailed if X goes over a threshold, and the instance can be shutdown after another threshold.
What I do is set up billing alerts through CloudWatch. I have $25/month in personal AWS usage paid for by my company (to encourage people to learn) and I set an alert when my monthly usage has hit $20 (which just went off yesterday).
The billing and cost management page should show you which regions you are incurring costs from on an ongoing basis.
But yeah, you have to know about all of this to use it. They should probably set a default alert at about $25/month on every new account, then let you change or delete it if you want.
Also their documentation. I frankly find it a personal achievement to hear of people successfully navigating their documentation to a working solution.
Just like you, I got burned for about a hundred dollars whenever they switched their UI for EC2 to only show instances per region. I have no idea when that change happened, but they weren't loud enough announcing it.
While they're desperately lacking in good getting started documentation, the reference docs are some of the best in the industry. I'll grant they're not pretty, but they cover everything in detail.
Billing alerts and learning to use the CLI largely remove the issue of ghost resource usage. If you use AWS beyond the basics, it is worth investing the time to get the CLI setup and use it in favor of the web interface.
I got stung for over $100 just as a casual user, because I never guessed that I had to click through all the (slow loading) regions to see the instances and volumes and snapshots I might have burning money.
The web interface is a total clusterfuck.