Partially correct. A private group is building high speed rail to connect Vegas to the Inland Empire. Construction has started and expected to be complete in 2028.
Las Vegas is basically on the California border and exists mainly because it's on the California border, so all the people in Southern California can go to the place where gambling is legal. It's an outlier that both doesn't get you a national high speed rail network and evidently doesn't require federal involvement to happen regardless.
https://www.dot.nv.gov/projects-programs/transportation-proj...
https://www.brightlinewest/