I've been working in this industry for nearly 45 years now. I still see endemic vulnerability to single points of failure, and little recognition of that.
Heck, the SolarWinds hack was first discovered by a security company because it had compromised their own internal systems and gone undetected for some time.
But a key aspect of this is that one does not develop software for airplanes the same way and with the same constraints/goals as other areas of software engineering.
If anything, aerospace engineering is a prime example of how software can be made more reliable by tolerating failures instead of relying on it not to fail, to come back to GP's point about failure-tolerant designs.
Exactly. I often have a hard time getting this point across, glad I succeeded.
Boeing really aren't a good example for anything besides negligence and how to game regulators.