> The fact that so many popular sites/services are experiencing issues due to a single AZ failure makes me think that there is a serious shortage of good cloud architects/engineers in the industry.

Not really.

What's more likely is that their companies have other priorities. Multi-AZ architectures are more expensive to run, but that's normally not the issue. What's really costly is testing their assumptions.

Sure, by deploying your system in a Kubernetes clusters spread across 3 AZs and a HA database you are supposedly covered against failures. Except that when it actually happened, turns out your system couldn't really survive a sudden 30% capacity loss like you expected, and the ASG churning is now causing havoc with the pods who did survive.

Complex systems often fail in non-trivial ways. If you are not chaos-monkeying regularly, you won't know about those cases until they happen. At which time it's too late.