While I didn't work on AWS, I did intern on the retail side of Amazon, and there's definitely this sort of monitoring in place. Surely somebody was paged. And even if not, this is "just" the cost explorer estimations, not what is ending up on folk's bills.

I learned about <https://en.wikipedia.org/wiki/2011_T%C5%8Dhoku_earthquake_an...> from alarms like this, as sales in Japan almost entirely stopped.

I've been told a tale of another incident where some customer ran some huge cpu-intensive workload that didn't do any networking. It caused various alarms to fire because it "looked like" a part of the network was idle (potentially indicating some sort of networking failure)

It's generally (in the broad sense) easy to add alarms for things going wrong, but in my experience anomaly detectors are just as likely to fire from other weird things like that happening.