[cjbprime]

We're told that MCAS only activates with the autopilot already off.

I agree with you that pilot training doesn't seem to be a plausible answer given that the Lion Air crash was world news, resulting in retraining, and yet that wasn't enough.

[etep]

Thank you for the insight! Just for clarity, I'm using "autopilot" as a catch-all term that refers the automated systems that plausibly seem to have caused these crashes.

[alexbecker]

...which is a pretty confusing thing to do, given that there are multiple such systems, one of which is conventionally called "autopilot".