> - training for the 737-8 and -9 was just short of non existent because in practice, these planes don’t fly differently.

Have you read this complaint from an actual pilot?

https://news.ycombinator.com/item?id=19374386

Quoting the HN post:

"My post flight evaluation is that we lacked the knowledge to operate the aircraft in all weather and aircraft states safely.

The instrumentation is completely different - My scan was degraded, slow and labored having had no experience w/ the new ND (Navigation Display) and ADI (Attitude Director Indicator) presentations/format or functions (manipulation between the screens and systems pages were not provided in training materials. If they were, I had no recollection of that material).

We were unable to navigate to systems pages and lacked the knowledge of what systems information was available to us in the different phases of flight. Our weather radar competency was inadequate to safely navigate significant weather on that dark and stormy night. These are just a few issues that were not addressed in our training."