They do fail catastrophically. E.g. https://en.wikipedia.org/wiki/Northeast_blackout_of_2003
I think you could argue AWS is more complex than the electrical grid, but even if it's not, the grid has had several decades to iron out kinks and AWS hasn't. AWS also adds a ton of completely new services each year in addition to adding more capacity. E.g. I bet these DNS Enactors have become more numerous and their plans became much larger than when they were first developed, which has greatly increased the odds of experiencing this issue.
Okay I concede that the power grid was a poor example but clearly the internet is not. No one pointed out a counter for teh internet
Some of the biggest failures have been BGP leaks/hijacks. E.g. https://www.ripe.net/about-us/news/youtube-hijacking-a-ripe-...
This has gotten significantly better in recent years, but it used to be possible and common for a single misbehaving AS to cause global issues.