Many teams are incompetently managed, and staffed with those who are "retired in place".
There is much talk about One Boeing and RAA, but in fact more often different groups are defined by their antipathy toward other groups, and management strives to avoid blame more than anything.
Managers shift jobs frequently to avoid having to live with the consequences of poor decisions.
Some teams develop using antiquated technologies that you might assume no one has used for 30+ years.
It can be very difficult, though possible, to effect change in the processes, tools, environment, and other factors that contribute to the success of projects.
It's as if none of the leaders has read any of the canon on software project management, and so they don't even know that their bad decisions are cliches.
Teams lack the authority to address most of these issues, and any change requires approval through at least 4 layers of management, and possibly one or more steering committees.
No one even knows how to correctly measure productivity so sometimes they will replace 1 productive person with salary N with 3+ non-productive persons with salary N/2. I've heard of teams where 1 level 4 was doing 90% of the work on the team, and management (not even direct management) chose to "lay off" that individual, and now the team has hired 2-4 replacements level 1-2 employees, and they (of course) aren't able to do even a significant fraction of the work.
I know of instances where senior high-salary employees are pushed out of the company as a short-sighted cost-saving measure. Many junior employees don't even get a mentoring or knowledge transfer period, because for complex projects this could require a year or more of overlap, and often < 2 weeks is allocated.