Re: "This is what happens when you scrimp on software dev, testing and docs"
This is a popular narrative for a site viewed by many software developers but in this case completeley innacurate. The problem was not the quality of the MCAS software implementation. The software did what it was specified to do. The problem was a poor system design and safety/risk analysis, poor change control because changes occured to the MCS operation without being properly assessed for their impact and poor regulatory oversight and checking.
Given what it did there is no way that MCAS should have been designed in such a way as being vulnerable to a single failure and there is no way that this shoudl not have been picke dup as a problem in testing and analysis.
There were a lot of problems in the development process that were responsible for this but not so far at least in the software aspects.