That report is obvious bullshit and you should be able to discern that immediately. It ranks countries on “ healthcare, education, technology access, working conditions, and social protection” and then calls that “social mobility”. Zero actual analysis of intra- or inter-generational wealth variance.

Interesting.

The OECD have a better report :

https://www.oecd.org/centrodemexico/medios/44582910.pdf

From page 5 Australia ranks #2 and Canada #5 and the US is #10.

That's on intergenerational income quintile mobility.