How is this different from extra safety features available as option packages for automobiles?
https://www.nytimes.com/interactive/2019/03/13/world/boeing-...
Look at the charts above. Both pilots "fought" with the controls, correcting the plane course, then believing "it's corrected now" and then the plane sunk again and again.
To extend (torture?) the automotive analogy, it would be as if the manufacturer substituted a new braking system that required preheating the rotors, installed software to automatically ride the brakes for the first 2 miles of driving in order to get that preheat done, then sold an optional safety feature to verify that the brakes were at the proper temperature.
The old way worked just fine without need for “emulation”. The new airframe required some software to mimic the old one, but they decided to charge you for the add-on to make sure that their band-aid worked reliably.
Yes, lane-keeping and auto-braking are not mandated. I expect they will be within a few years.
I think I could have avoided this situation by turning on the left-turn signal to disable the lane-assist and generally its a good idea to use the indicator even when just passing a bike -- but that's not something I normally need to do to avoid this particular failure mode ...
That's exactly what you had to do according to the regulations.
That thing has a good default that is still overridable by the brute force (force that's less than the force needed to steer if the power assist fails altogether).
The adaptive cruise control in my VW actually gets confused sometimes. Drove through a puddle at the beach last year and it jammed on the brakes. Glad nobody rear-ended me.