The private sector also comes in flavors like ULA, Lockheed Martin, or Boeing. Given that NASA was prevented from continuing their successful approach in favor of building what Congress wanted to steer money to major private companies, any explanation which focuses on the sector alone is guaranteed to be wrong. What matters is how the incentives are structured: giving money to a contractor to keep people employed in certain areas won’t yield successful launch systems the way paying for successful launches will.

(And, no, it’s not as simple as saying the root cause is government: those companies spend enormous amounts of money trying to influence the government so the relationship again is not that simple.)