Design flaws that you don't know about yet are still design flaws.
I'm sure there are plenty of "accepted design flaws" in SpaceX vehicles. Hopefully SpaceX engineers are better at calculating the probabilities than NASA was, but I would not volunteer for early missions.
The two programs don’t manage risk the same way. You’re picturing a younger NASA trying to do the same process as led to the first space shuttle launch.
With the Challenger disaster, the contractor's engineering team that developed the booster gave a no-go for launch and NASA administrators showed off their engineering skills by using social engineering to trick an unqualified and unapproved employee of the contractor into signing the form to go for launch. That's far worse than being bad at calculating the safety risks; the specifically overruled the decision by the people that were good at calculating the safety risk.
Source: Truth, Lies, and O-Rings by Allan J. McDonald, James R. Hansen, and Jonathan Yen
Bad things happen, and spaceflight is a hard problem. But that’s not what killed two Shuttle crews.
I'm sure there are plenty of "accepted design flaws" in SpaceX vehicles. Hopefully SpaceX engineers are better at calculating the probabilities than NASA was, but I would not volunteer for early missions.
Source: Truth, Lies, and O-Rings by Allan J. McDonald, James R. Hansen, and Jonathan Yen