NASA is a political jobs program from a funding perspective. There isn't any way around that.
This creates uncertainties, distractions and perverse incentives all around:
0. Everything is dramatically complicated by the artificial divisions of work across states needed to get enough political support. Grossly inefficient from the start, and inflexible into perpetuity.
1. Initial schedules are incentivized to be unrealistic, and not reflective of hard analysis/planning, in order to get funding. Easier to deal with the real details and expand schedules later, even though nobody wants that to be the process.
2. Essentially a cost plus (or cost even) program. There is no hard limit on cost, since the further along a project is, the easier it is to raise its budget, especially along with schedule delays.
3. Creativity flows to the most basic constraint. The most basic constraint is political will to fund, so top level attention goes to managing/manipulating up.
When NASA's hard constraint was time (getting to the moon first), creativity went there. They were never cheap, but they did operate with incredible speed.
Whereas any private company's basic constraints are relative profitability in terms of net return in a given time frame, so creativity goes to both speed and cost.
4. Boeing and other traditional large NASA contractors operated for decades under NASA's politically driven, cost plus umbrella, so continue to suffer from, and reinforce, NASA's problems.
This culture is hard to break, even after switching to a flat cost (still time flexible) regime. See recent Boeing troubles. Not just throw away rockets, but a much delayed, over budget, wonky one-way manned spaceship!! Ouch!