Please, all indications are that Boeing skipped on regulation, testing and design all the way through. It also included valuable sensors as a "value add in" instead of in the base model. It also disincentivized pilot training and a host of other security measures because they knew client would balk at the costs being passed down, due to Boeing's own design decisions, most notably the "hack" of using the 737 type, despite large modifications to the entire aircraft.

Essentially, Boeing made a bunch of cost cutting decisions and cut every corner they could. Patches were developed and changes were suggested, but were delayed or cancelled due to business and political reasons.