Recent SpaceX IPO filings put that 'tiny fraction' at about 1/3 or 1/2 of SLS. $15B total investment with about $4-5B of that figure from US gov. Is starship more than 1/2 or 1/3 of the way to a human rated Artemis II style mission? The main reason starship costs less to test (apart from the SLS jobs program baggage) is because of design choices which prevent it from performing such a mission without significant further tech development.

'5 times as long' is dubious too. SpaceX claims to have been working on the design since 2012 vs 2011 for SLS. Ultimately though the start date of a complex program is not well defined, as early conceptual design stages can take years without leaving the drawing board. Government needs to put a start date on such efforts for legal/budget reasons, but a private company does not.

Also relevant - SpaceX has been given a lot of tech and expertise from NASA at a tiny fraction of the cost and time it would have required them to develop it themselves. Therefore, the costs of NASA programs like space shuttle actually includes some of the development costs of SpaceX.

Both programs pale in comparison to Saturn V, which was faster, cheaper, and more technically demanding at the time.