As somebody who knows nothing about how planes fly, this story was really interesting:
https://www.vox.com/business-and-fin...ndal-explained
TLDR in 4 points:
1. There is a huge incentive for the 737 Max to be judged the same as other 737's, and therefore require no retraining for pilots and airlines.
2. The 737 Max doesn't fly like other boeing 737's due to design compromises to make it more efficient. Boeing tried to use software to get around this plane flying differently, and the software is glitchy, which caused the two crashes. At the same time, Pilots had reported this issue anonymously before the crashes. Some pilots believe there should be formal training required to fly a 737 considering how different the plane is and the reliance on software.
3. Boeing was highly involved in the FAA review of this, performing many of the tasks. I think many people assume the FAA is completely independent in their reviews. This is definitely not the case.
4. Boeing also made a critical error light that would help in detecting a malfunction in the software optional. Carriers in developing countries didn't select.
Overall, it seems like separation of duties between regulators and industry would have solved this.