[thegrim22]

There's also a political angle since NASA represents the US. If anything goes wrong with a NASA project it's a massive propaganda opportunity for agitators and rival countries to mass spam the internet about how horrible America has become, what a laughing stock, etc., etc., doing everything they can to push their anti-US propaganda as hard as they can. There's more repercussions for NASA to fail at something than a private company.

[inglor_cz]

This is an interesting angle that I haven't thought of.

NASA projects carry a lot more gravitas than "move fast and break things" Musk projects. If something explodes at SpaceX, as long as people aren't hurt, no one really cares. People who dislike Musk will simply point at the debris and say: "We told you he's an idiot" and people who like him will rush to his defense, but the standing of the US as a whole isn't on the line.