Quadruple bogey for the course
Bad management. Boeing's corporate culture and decentralized model is certainly to blame for a lot of their problems. RL mentioned quality control, and that really is the issue here. It must be engrained into the manufacturing process of any company, especially one where human lives are directly at risk. There’s nothing inherently wrong with letting the bottom line be important in how you run your shop, but you can’t put blinders on and cut corners on QC and safety.
Fortunately, the vast majority of business leaders in the world understand that failures in QC can not only hurt people, it can put them out of business.