Unfortunately NASA doesn't have the ability to even appear to fail explosively while SpaceX can afford to laugh about it. Any significant explosion would have the tech illiterate Congress breathing down their necks.
It's the curse of waterfall budgeting. A democratic government with typical constraints wants to minimize spending and to have all spending fully accounted for in advance.
"I dunno, maybe it will blow up this time?" is not an acceptable line-item under either standard.
Therefore, budgets must plan for success and design failure out of the process. Minimizing risk maximizes process and cost, ironically sacrificing the very low-cost public policy goal at the feet of risk intolerance. Instead of fifty SLS launches, of which the first dozen or so might fail as learning experiences, we get five that all must go flawlessly.
True "risky" development is reserved for programs of true national urgency (e.g. the original defense focus of the space race) or for programs that can operate well outside the public's watchful eye.
I don't think you can assert that NASA hasn't or wouldn't fall to Pournelle's Iron Law of Bureaucracy. What makes NASA special to be immune to such dysfunction?