I'll elaborate: human error is not all reducible to a UX problem, at least not in any meaningful sense in casting blame at AWS here for causing the user's error. Giving users an explanation of their actions at the top of the page is not particularly bad UX, it seems adequate. If course they could do more, modals that say "here's your estimated costs for the action you're taking" and that might be better. But then again that might not be practical across the range of AWS modules, and a user that if ignores their bills and bank statements for most of a year might easily ignore those notices as well.
If you define every mistake a user makes as a UX problem then you've defined it broadly enough that it loses meaning. I doubt that's you're overall intent, but in claiming the user's failure to read the top of the page was a UX problem you're crossing over into that territory.
I might be more sympathetic if the user wasn't so lacking in awareness that they also didn't read their bills and bank statements for so many months, and didn't take the hour of time upfront that was ultimately necessary to understand part of a massively complex system. No reasonable level of UX design would have fixed all of that.