Also looks like the paper explicitly said it wasn't doing a public/private sector comparison so much as observing that SpaceX doing repeatable stuff in LEO on short timelines delivered without the cost overruns of NASA doing more complex one-offs over longer timelines and concluding that, surprise surprise, the repeatable stuff and incremental improvement stuff had much better cost control than the deep space science missions and space station enhancements. Yes, if you look at the raw number of missions SpaceX has operated, most of them have been successful Falcon 9 launches and most of them have been to deploy minisats to a standard design, and its track record of these is excellent (including adding reusability). NASA's track record would look a lot better if it mostly launched satellite constellations to LEO too and better still if it held off on planning anything in deep space, but that's not really what NASA is for. If you look at SpaceX in terms of private programmes rather than missions, the Falcon 9 is outstanding and the Starlink minisats work, the Falcon Heavy seems fine, Starship has been going on a very long time (including work before the Starship name was coined like the the Raptor engine) and hasn't achieved anything useful yet, and the stated goal of going to Mars hasn't got off the drawing board. But they're very, very good at building and delivering significant improvements on the repeatable stuff that isn't NASAs focus

Also, if you're doing a fair comparison between public and private sector you've got to consider all the launch startups that aren't SpaceX, including the ones that haven't successfully launched...