So what accounts for the difference?

Maybe it’s just a question of priorities.

When competence is rewarded, you get more of it. When the ability to play internal politics is what gets you ahead, then you get more of that. 

SpaceX has clear goals, short deadlines and clear lines of responsibility. Boeing’s culture, once one that revered engineering, has become one that worships byzantine corporate politics — where you’re more likely to get fired over DEI infractions than over job performance.